Past research
Alp’s past research on topics ranging from diamond color centers to quantum optics and waveguide QED with superconducting circuits and optomechanical quantum transduction.
Quantum optics with superconducting circuits
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Physical Review X 11, 041043 (2021)
@article{ferreira_collapse_2021, title = {Collapse and {Revival} of an {Artificial} {Atom} {Coupled} to a {Structured} {Photonic} {Reservoir}}, volume = {11}, url = {https://doi.org/10.1103/PhysRevX.11.041043}, doi = {10.1103/PhysRevX.11.041043}, journal = {Physical Review X}, pages = {041043}, author = {Ferreira, V. S. and Banker, J. and Sipahigil, A. and Matheny, M. H. and Keller, A. J. and Kim, E. and Mirhosseini, M. and Painter, O.}, month = dec, year = {2021}, arxiv = {2001.03240} }A structured electromagnetic reservoir can result in novel dynamics of quantum emitters. In particular, the reservoir can be tailored to have a memory of past interactions with emitters, in contrast to memory-less Markovian dynamics of typical open systems. In this Article, we investigate the non-Markovian dynamics of a superconducting qubit strongly coupled to a superconducting slow-light waveguide reservoir. Tuning the qubit into the spectral vicinity of the passband of this waveguide, we find non-exponential energy relaxation as well as substantial changes to the qubit emission rate. Further, upon addition of a reflective boundary to one end of the waveguide, we observe revivals in the qubit population on a timescale 30 times longer than the inverse of the qubit’s emission rate, corresponding to the round-trip travel time of an emitted photon. By tuning of the qubit-waveguide interaction strength, we probe a crossover between Markovian and non-Markovian qubit emission dynamics. These attributes allow for future studies of multi-qubit circuits coupled to structured reservoirs, in addition to constituting the necessary resources for generation of multiphoton highly entangled states.
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Physical Review X 11, 011015 (2021)
@article{kim_quantum_2021, title = {Quantum {Electrodynamics} in a {Topological} {Waveguide}}, volume = {11}, url = {https://doi.org/10.1103/PhysRevX.11.011015}, doi = {10.1103/PhysRevX.11.011015}, journal = {Physical Review X}, pages = {011015}, author = {Kim, E. and Zhang, X. and Ferreira, V. S. and Banker, J. and Iverson, J. K. and Sipahigil, A. and Bello, M. and González-Tudela, A. and Mirhosseini, M. and Painter, O.}, month = jan, year = {2021}, arxiv = {2005.03802} }While designing the energy-momentum relation of photons is key to many linear, non-linear, and quantum optical phenomena, a new set of light-matter properties may be realized by employing the topology of the photonic bath itself. In this work we investigate the properties of superconducting qubits coupled to a metamaterial waveguide based on a photonic analog of the Su-Schrieffer-Heeger model. We explore topologically-induced properties of qubits coupled to such a waveguide, ranging from the formation of directional qubit-photon bound states to topology-dependent cooperative radiation effects. Addition of qubits to this waveguide system also enables direct quantum control over topological edge states that form in finite waveguide systems, useful for instance in constructing a topologically protected quantum communication channel. More broadly, our work demonstrates the opportunity that topological waveguide-QED systems offer in the synthesis and study of many-body states with exotic long-range quantum correlations.
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Nature 569, 692–697 (2019)
@article{mirhosseini_cavity_2019, title = {Cavity quantum electrodynamics with atom-like mirrors}, volume = {569}, url = {https://doi.org/10.1038/s41586-019-1196-1}, doi = {10.1038/s41586-019-1196-1}, journal = {Nature}, pages = {692--697}, author = {Mirhosseini, M. and Kim, E. and Zhang, X. and Sipahigil, A. and Dieterle, P. B. and Keller, A. J. and Asenjo-Garcia, A. and Chang, D. E. and Painter, O.}, month = may, year = {2019}, arxiv = {1809.09752} }Waveguide quantum electrodynamics studies photon-mediated interactions of quantum emitters in a one-dimensional radiation channel. Although signatures of such interactions have been observed previously in a variety of physical systems, observation of coherent cooperative dynamics has been obscured by radiative decay of atoms into the waveguide. Employing transmon qubits as artificial atoms coupled to a microwave coplanar waveguide, here we observe dynamical oscillations in an open system where a designated probe qubit interacts with an entangled dark state of an array of qubits which effectively traps radiation as an atomic cavity. The qubit-cavity system is shown to achieve a large cooperativity of C=172 due to collective enhancement of photon-mediated interactions, entering the strong coupling regime. The quantum coherence of the dark state cavity is also explored through its nonlinear response at the single-excitation level. With realistic refinements, this system is suitable for studying the many-body dynamics of large (N>10) quantum spin chains, synthesizing highly non-classical radiation fields on demand, and implementing universal quantum logic operations with high fidelity on information encoded within decoherence-free subspaces.
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Nature Communications 9, 3706 (2018)
@article{mirhosseini_superconducting_2018, title = {Superconducting metamaterials for waveguide quantum electrodynamics}, volume = {9}, url = {https://doi.org/10.1038/s41467-018-06142-z}, doi = {10.1038/s41467-018-06142-z}, journal = {Nature Communications}, pages = {3706}, author = {Mirhosseini, M. and Kim, E. and Ferreira, V. S. and Kalaee, M. and Sipahigil, A. and Keller, A. J. and Painter, O.}, month = sep, year = {2018}, arxiv = {1802.01708} }Embedding tunable quantum emitters in a photonic bandgap structure enables control of dissipative and dispersive interactions between emitters and their photonic bath. Operation in the transmission band, outside the gap, allows for studying waveguide quantum electrodynamics in the slow-light regime. Alternatively, tuning the emitter into the bandgap results in finite-range emitter–emitter interactions via bound photonic states. Here, we couple a transmon qubit to a superconducting metamaterial with a deep sub-wavelength lattice constant ( λ /60). The metamaterial is formed by periodically loading a transmission line with compact, low-loss, low-disorder lumped-element microwave resonators. Tuning the qubit frequency in the vicinity of a band-edge with a group index of n g = 450, we observe an anomalous Lamb shift of −28 MHz accompanied by a 24-fold enhancement in the qubit lifetime. In addition, we demonstrate selective enhancement and inhibition of spontaneous emission of different transmon transitions, which provide simultaneous access to short-lived radiatively damped and long-lived metastable qubit states.
* Equal contribution
Quantum transduction
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Nature 588, 599–603 (2020)
@article{mirhosseini_superconducting_2020, title = {Superconducting qubit to optical photon transduction}, volume = {588}, url = {https://www.nature.com/articles/s41586-020-3038-6}, doi = {10.1038/s41586-020-3038-6}, journal = {Nature}, number = {7839}, pages = {599--603}, issn = {0028-0836, 1476-4687}, author = {Mirhosseini, Mohammad and Sipahigil, Alp and Kalaee, Mahmoud and Painter, Oskar}, month = dec, year = {2020}, arxiv = {2004.04838} }Bidirectional conversion of electrical and optical signals lies at the foundation of the global internet. Such converters are employed at repeater stations to extend the reach of long-haul fiber optic communication systems and within data centers to exchange high-speed optical signals between computers. Likewise, coherent microwave-to-optical conversion of single photons would enable the exchange of quantum states between remotely connected superconducting quantum processors, a promising quantum computing hardware platform. Despite the prospects of quantum networking, maintaining the fragile quantum state in such a conversion process with superconducting qubits has remained elusive. Here we demonstrate the conversion of a microwave-frequency excitation of a superconducting transmon qubit into an optical photon. We achieve this using an intermediary nanomechanical resonator which converts the electrical excitation of the qubit into a single phonon by means of a piezoelectric interaction, and subsequently converts the phonon to an optical photon via radiation pressure. We demonstrate optical photon generation from the qubit with a signal-to-noise greater than unity by recording quantum Rabi oscillations of the qubit through single-photon detection of the emitted light over an optical fiber. With proposed improvements in the device and external measurement set-up, such quantum transducers may lead to practical devices capable of realizing new hybrid quantum networks, and ultimately, distributed quantum computers.
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Science 370, 840–843 (2020)
@article{maccabe_phononic_2020, title = {Nano-acoustic resonator with ultralong phonon lifetime}, volume = {370}, url = {https://doi.org/10.1126/science.abc7312}, doi = {10.1126/science.abc7312}, journal = {Science}, number = {6518}, pages = {840--843}, author = {MacCabe, G. S. and Ren, H. and Luo, J. and Cohen, J. D. and Zhou, H. and Sipahigil, A. and Mirhosseini, M. and Painter, O.}, month = nov, year = {2020}, arxiv = {1901.04129} }The ideal platform for quantum-computing and quantum-sensing applications is likely to be a hybrid system that combines the best features of different components. Superconducting circuits are relatively advanced, and finding components that can control and manipulate the microwaves will be essential. MacCabe et al. explored the use of high-quality microresonators in which the acoustic environment could be engineered such that the phonon lifetime could be extended to more than 1 second. Operating at microwave frequencies of 5 gigahertz, these quantum acoustic-dynamic devices could be coupled with superconducting circuits. Science , this issue p. 840
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Physical Review A 100, 012307 (2019)
@article{covey_microwave-to-optical_2019, title = {Microwave-to-optical conversion via four-wave mixing in a cold ytterbium ensemble}, volume = {100}, url = {https://doi.org/10.1103/PhysRevA.100.012307}, doi = {10.1103/PhysRevA.100.012307}, journal = {Physical Review A}, pages = {012307}, author = {Covey, J. P. and Sipahigil, A. and Saffman, M.}, month = jul, year = {2019}, arxiv = {1904.08999} }Interfacing superconducting qubits with optical photons requires noise-free microwave-to-optical transducers, a technology currently not realized at the single-photon level. We propose to use four-wave-mixing in an ensemble of cold ytterbium (Yb) atoms prepared in the metastable ’clock’ state. The parametric process uses two high-lying Rydberg states for bidirectional conversion between a 10 GHz microwave photon and an optical photon in the telecommunication E-band. To avoid noise photons due to spontaneous emission, we consider continuous operation far detuned from the intermediate states. We use an input-output formalism to predict conversion efficiencies of ≈50% with bandwidths of ≈100 kHz.
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Physical Review Applied 11, 034044 (2019)
@article{covey_telecom-band_2019, title = {Telecom-band quantum optics with ytterbium atoms and silicon nanophotonics}, volume = {11}, url = {https://doi.org/10.1103/PhysRevApplied.11.034044}, doi = {10.1103/PhysRevApplied.11.034044}, journal = {Physical Review Applied}, pages = {034044}, author = {Covey, J. P. and Sipahigil, A. and Szoke, S. and Sinclair, N. and Endres, M. and Painter, O.}, month = mar, year = {2019}, arxiv = {1810.12821} }Wavelengths in the telecommunication window ( 1.25-1.65 microns) are ideal for quantum communication due to low transmission loss in fiber networks. To realize quantum networks operating at these wavelengths, long-lived quantum memories that couple to telecom-band photons with high efficiency need to be developed. We propose coupling neutral ytterbium atoms, which have a strong telecom-wavelength transition, to a silicon photonic crystal cavity. Specifically, we consider the 3P0-3D1 transition in neutral 171Yb to interface its long-lived nuclear spin in the metastable 3P0 ’clock’ state with a telecom-band photon at 1.4 microns. We show that Yb atoms can be trapped using a short wavelength ( 470 nm) tweezer at a distance of 350 nm from the silicon photonic crystal cavity. At this distance, due to the slowly decaying evanescent cavity field at a longer wavelength, we obtain a single-photon Rabi frequency of g/(2pi) 100 MHz and a cooperativity of C 47 while maintaining a high photon collection efficiency into a single mode fiber. The combination of high system efficiency, telecom-band operation, and long coherence times makes this platform well suited for quantum optics on a silicon chip and long-distance quantum communication.
* Equal contribution
Diamond color centers
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Science 362, 662–665 (2018)
@article{evans_photon-mediated_2018, title = {Photon-mediated interactions between quantum emitters in a diamond nanocavity}, volume = {362}, url = {https://doi.org/10.1126/science.aau4691}, doi = {10.1126/science.aau4691}, journal = {Science}, number = {6415}, pages = {662--665}, author = {Evans, R. E. and Bhaskar, M. K. and Sukachev, D. D. and Nguyen, C. T. and Sipahigil, A. and Burek, M. J. and Machielse, B. and Zhang, G. H. and Zibrov, A. S. and Bielejec, E. and Park, H. and Loncar, M. and Lukin, M. D.}, month = nov, year = {2018}, arxiv = {1807.04265} }The development of scalable quantum systems will require the ability to control the interactions between the individual quantum building blocks of the system. Evans et al. used a pair of silicon vacancy centers embedded in a diamond nanocavity to show that interactions between the quantum emitters can be mediated optically (see the Perspective by Lodahl). Such optical control provides a speed advantage as well as the potential to develop an integrated platform for future quantum communication and quantum networking. Science , this issue p. 662 ; see also p. 646
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Physical Review B 97, 205444 (2018)
@article{meesala_strain_2018, title = {Strain engineering of the silicon-vacancy center in diamond}, volume = {97}, url = {https://doi.org/10.1103/PhysRevB.97.205444}, doi = {10.1103/PhysRevB.97.205444}, journal = {Physical Review B}, pages = {205444}, author = {Meesala, S. and Sohn, Y. and Pingault, B. and Shao, L. and Atikian, H. A. and Holzgrafe, J. and Gündoğan, M. and Stavrakas, C. and Sipahigil, A. and Chia, C. and Evans, R. and Burek, M. J. and Zhang, M. and Wu, L. and Pacheco, J. L. and Abraham, J. and Bielejec, E. and Lukin, M. D. and Atatüre, M. and Loncar, M.}, month = may, year = {2018}, arxiv = {1801.09833} }We control the electronic structure of the silicon-vacancy (SiV) color-center in diamond by changing its static strain environment with a nano-electro-mechanical system. This allows deterministic and local tuning of SiV optical and spin transition frequencies over a wide range, an essential step towards multi-qubit networks. In the process, we infer the strain Hamiltonian of the SiV revealing large strain susceptibilities of order 1 PHz/strain for the electronic orbital states. We identify regimes where the spin-orbit interaction results in a large strain suseptibility of order 100 THz/strain for spin transitions, and propose an experiment where the SiV spin is strongly coupled to a nanomechanical resonator.
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Physical Review Letters 120, 213603 (2018)
@article{lemonde_phonon_2018, title = {Phonon {Networks} with {Silicon}-{Vacancy} {Centers} in {Diamond} {Waveguides}}, volume = {120}, url = {https://doi.org/10.1103/PhysRevLett.120.213603}, doi = {10.1103/PhysRevLett.120.213603}, journal = {Physical Review Letters}, pages = {213603}, author = {Lemonde, M.-A. and Meesala, S. and Sipahigil, A. and Schuetz, M. J. A. and Lukin, M. D. and Loncar, M. and Rabl, P.}, month = may, year = {2018}, arxiv = {1801.01904} }We propose and analyze a novel realization of a solid-state quantum network, where separated silicon-vacancy centers are coupled via the phonon modes of a quasi-1D diamond waveguide. In our approach, quantum states encoded in long-lived electronic spin states can be converted into propagating phonon wavepackets and be reabsorbed efficiently by a distant defect center. Our analysis shows that under realistic conditions, this approach enables the implementation of high-fidelity, scalable quantum communication protocols within chip-scale spin-qubit networks. Apart from quantum information processing, this setup constitutes a novel waveguide QED platform, where strong-coupling effects between solid-state defects and individual propagating phonons can be explored at the quantum level.
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Nature Communications 9, 2012 (2018)
@article{sohn_controlling_2018, title = {Controlling the coherence of a diamond spin qubit through its strain environment}, volume = {9}, url = {https://doi.org/10.1038/s41467-018-04340-3}, doi = {10.1038/s41467-018-04340-3}, journal = {Nature Communications}, pages = {2012}, author = {Sohn, Y. I. and Meesala, S. and Pingault, B. and Atikian, H. A. and Holzgrafe, J. and Gündoğan, M. and Stavrakas, C. and Stanley, M. J. and Sipahigil, A. and Choi, J. and Zhang, M. and Pacheco, J. L. and Abraham, J. and Bielejec, E. and Lukin, M. D. and Atatüre, M. and Loncar, M.}, month = may, year = {2018}, arxiv = {1706.03881} }The uncontrolled interaction of a quantum system with its environment is detrimental for quantum coherence. For quantum bits in the solid state, decoherence from thermal vibrations of the surrounding lattice can typically only be suppressed by lowering the temperature of operation. Here, we use a nano-electro-mechanical system to mitigate the effect of thermal phonons on a spin qubit – the silicon-vacancy colour centre in diamond – without changing the system temperature. By controlling the strain environment of the colour centre, we tune its electronic levels to probe, control, and eventually suppress the interaction of its spin with the thermal bath. Strain control provides both large tunability of the optical transitions and significantly improved spin coherence. Finally, our findings indicate the possibility to achieve strong coupling between the silicon-vacancy spin and single phonons, which can lead to the realisation of phonon-mediated quantum gates and nonlinear quantum phononics.
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Applied Physics Letters 112, 203102 (2018)
@article{nguyen_all-optical_2018, title = {All-optical nanoscale thermometry with silicon-vacancy centers in diamond}, volume = {112}, url = {https://doi.org/10.1063/1.5029904}, doi = {10.1063/1.5029904}, journal = {Applied Physics Letters}, pages = {203102}, author = {Nguyen, C. T. and Evans, R. E. and Sipahigil, A. and Bhaskar, M. K. and Sukachev, D. D. and Agafonov, V. N. and Davydov, V. A. and Kulikova, L. F. and Jelezko, F. and Lukin, M. D.}, month = may, year = {2018}, arxiv = {1708.05419} }We demonstrate an all-optical thermometer based on an ensemble of silicon-vacancy centers (SiVs) in diamond by utilizing the sensitivity of the zero-phonon line wavelength to temperature, Δλ/ΔT=0.0124(2) nm K–1 [6.8(1) GHz K–1]. Using SiVs in bulk diamond, we achieve 70 mK precision at room temperature with a temperature uncertainty σT=360 mK/Hz. Finally, we use SiVs in 200 nm nanodiamonds as local temperature probes with 521 mK/Hz uncertainty and achieve sub-Kelvin precision. These properties deviate by less than 1% between nanodiamonds, enabling calibration-free thermometry for sensing and control of complex nanoscale systems.
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Physical Review Letters 119, 223602 (2017)
@article{sukachev_silicon-vacancy_2017, title = {Silicon-{Vacancy} {Spin} {Qubit} in {Diamond}: A {Quantum} {Memory} {Exceeding} 10 ms with {Single}-{Shot} {State} {Readout}}, volume = {119}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.119.223602}, doi = {10.1103/PhysRevLett.119.223602}, journal = {Physical Review Letters}, number = {22}, pages = {223602}, issn = {0031-9007, 1079-7114}, author = {Sukachev, D. D. and Sipahigil, A. and Nguyen, C. T. and Bhaskar, M. K. and Evans, R. E. and Jelezko, F. and Lukin, M. D.}, month = nov, year = {2017}, arxiv = {1708.08852} }The negatively-charged silicon-vacancy (SiV⁻) color center in diamond has recently emerged as a promising system for quantum photonics. Its symmetry-protected optical transitions enable creation of indistinguishable emitter arrays and deterministic coupling to nanophotonic devices. Despite this, the longest coherence time associated with its electronic spin achieved to date ( 250 ns) has been limited by coupling to acoustic phonons. We demonstrate coherent control and suppression of phonon-induced dephasing of the SiV⁻ electronic spin coherence by five orders of magnitude by operating at temperatures below 500 mK. By aligning the magnetic field along the SiV⁻ symmetry axis, we demonstrate spin-conserving optical transitions and single-shot readout of the SiV⁻ spin with 89% fidelity. Coherent control of the SiV⁻ spin with microwave fields is used to demonstrate a spin coherence time T₂ of 13 ms and a spin relaxation time T₁ exceeding 1 s at 100 mK. These results establish the SiV⁻ as a promising solid-state candidate for the realization of scalable quantum networks.
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Physical Review B 96, 081201(R) (2017)
@article{siyushev_optical_2017, title = {Optical and microwave control of germanium-vacancy center spins in diamond}, volume = {96}, url = {https://doi.org/10.1103/PhysRevB.96.081201}, doi = {10.1103/PhysRevB.96.081201}, journal = {Physical Review B}, pages = {081201(R)}, author = {Siyushev, P. and Metsch, M. H. and Ijaz, A. and Binder, J. and Bhaskar, M. K. and Sukachev, D. D. and Sipahigil, A. and Evans, R. E. and Nguyen, C. T. and Lukin, M. D. and Hemmer, P. R. and Palyanov, Y. N. and Kupriyanov, I. N. and Borzdov, Y. M. and Rogers, L. J. and Jelezko, F.}, month = aug, year = {2017}, arxiv = {1612.02947} }A solid-state system combining a stable spin degree of freedom with an efficient optical interface is highly desirable as an element for integrated quantum optical and quantum information systems. We demonstrate a bright color center in diamond with excellent optical properties and controllable electronic spin states. Specifically, we carry out detailed optical spectroscopy of a Germanium Vacancy (GeV) color center demonstrating optical spectral stability. Using an external magnetic field to lift the electronic spin degeneracy, we explore the spin degree of freedom as a controllable qubit. Spin polarization is achieved using optical pumping, and a spin relaxation time in excess of 20 μs is demonstrated. Optically detected magnetic resonance (ODMR) is observed in the presence of a resonant microwave field. ODMR is used as a probe to measure the Autler-Townes effect in a microwave-optical double resonance experiment. Superposition spin states were prepared using coherent population trapping, and a pure dephasing time of about 19 ns was observed. Prospects for realizing coherent quantum registers based on optically controlled GeV centers are discussed.
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Physical Review Applied 8, 024026 (2017)
@article{burek_fiber-coupled_2017, title = {A fiber-coupled diamond quantum nanophotonic interface}, volume = {8}, url = {https://doi.org/10.1103/PhysRevApplied.8.024026}, doi = {10.1103/PhysRevApplied.8.024026}, journal = {Physical Review Applied}, pages = {024026}, author = {Burek, M. J. and Meuwly, C. and Evans, R. E. and Bhaskar, M. K. and Sipahigil, A. and Meesala, S. and Sukachev, D. D. and Nguyen, C. T. and Bielejec, E. and Lukin, M. D. and Loncar, M.}, month = aug, year = {2017}, arxiv = {1612.05285} }Color centers in diamond provide a promising platform for quantum optics in the solid state, with coherent optical transitions and long-lived electron and nuclear spins. Building upon recent demonstrations of nanophotonic waveguides and optical cavities in single-crystal diamond, we now demonstrate on-chip diamond nanophotonics with a high efficiency fiber-optical interface, achieving > 90% power coupling at visible wavelengths. We use this approach to demonstrate a bright source of narrowband single photons, based on a silicon-vacancy color center embedded within a waveguide-coupled diamond photonic crystal cavity. Our fiber-coupled diamond quantum nanophotonic interface results in a high flux of coherent single photons into a single mode fiber, enabling new possibilities for realizing quantum networks that interface multiple emitters, both on-chip and separated by long distances.
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Physical Review Letters 118, 223603 (2017)
@article{bhaskar_quantum_2017, title = {Quantum {Nonlinear} {Optics} with a {Germanium}-{Vacancy} {Color} {Center} in a {Nanoscale} {Diamond} {Waveguide}}, volume = {118}, url = {https://doi.org/10.1103/PhysRevLett.118.223603}, doi = {10.1103/PhysRevLett.118.223603}, journal = {Physical Review Letters}, pages = {223603}, author = {Bhaskar, M. K. and Sukachev, D. D. and Sipahigil, A. and Evans, R. E. and Burek, M. J. and Nguyen, C. T. and Rogers, L. J. and Siyushev, P. and Metsch, M. H. and Park, H. and Jelezko, F. and Loncar, M. and Lukin, M. D.}, month = may, year = {2017}, arxiv = {1612.03036} }We demonstrate a quantum nanophotonics platform based on germanium-vacancy (GeV) color centers in fiber-coupled diamond nanophotonic waveguides. We show that GeV optical transitions have a high quantum efficiency and are nearly lifetime-broadened in such nanophotonic structures. These properties yield an efficient interface between waveguide photons and a single GeV without the use of a cavity or slow-light waveguide. As a result, a single GeV center reduces waveguide transmission by 18 ± 1% on resonance in a single pass. We use a nanophotonic interferometer to perform homodyne detection of GeV resonance fluorescence. By probing the photon statistics of the output field, we demonstrate that the GeV-waveguide system is nonlinear at the single-photon level.
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Nature Communications 8, 15376 (2017)
@article{schroder_scalable_2017, title = {Scalable {Focused} {Ion} {Beam} {Creation} of {Nearly} {Lifetime}-{Limited} {Single} {Quantum} {Emitters} in {Diamond} {Nanostructures}}, volume = {8}, url = {https://doi.org/10.1038/ncomms15376}, doi = {10.1038/ncomms15376}, journal = {Nature Communications}, pages = {15376}, author = {Schröder, T. and Trusheim, M. E. and Walsh, M. and Li, L. and Zheng, J. and Schukraft, M. and Pacheco, J. L. and Camacho, R. M. and Bielejec, E. S. and Sipahigil, A. and Evans, R. E. and Sukachev, D. D. and Nguyen, C. T. and Lukin, M. D. and Englund, D.}, month = may, year = {2017}, arxiv = {1610.09492} }The controlled creation of defect centre—nanocavity systems is one of the outstanding challenges for efficiently interfacing spin quantum memories with photons for photon-based entanglement operations in a quantum network. Here we demonstrate direct, maskless creation of atom-like single silicon vacancy (SiV) centres in diamond nanostructures via focused ion beam implantation with ∼32 nm lateral precision and <50 nm positioning accuracy relative to a nanocavity. We determine the Si+ ion to SiV centre conversion yield to be ∼2.5% and observe a 10-fold conversion yield increase by additional electron irradiation. Low-temperature spectroscopy reveals inhomogeneously broadened ensemble emission linewidths of ∼51 GHz and close to lifetime-limited single-emitter transition linewidths down to 126±13 MHz corresponding to ∼1.4 times the natural linewidth. This method for the targeted generation of nearly transform-limited quantum emitters should facilitate the development of scalable solid-state quantum information processors.
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Science 354, 847–850 (2016)
@article{sipahigil_integrated_2016, title = {An integrated diamond nanophotonics platform for quantum optical networks}, volume = {354}, url = {https://doi.org/10.1126/science.aah6875}, doi = {10.1126/science.aah6875}, journal = {Science}, number = {6314}, pages = {847--850}, author = {Sipahigil, A. and Evans, R. E. and Sukachev, D. D. and Burek, M. J. and Borregaard, J. and Bhaskar, M. K. and Nguyen, C. T. and Pacheco, J. L. and Atikian, H. A. and Meuwly, C. and Camacho, R. M. and Jelezko, F. and Bielejec, E. and Park, H. and Loncar, M. and Lukin, M. D.}, month = nov, year = {2016}, arxiv = {1608.05147} }Technologies that exploit the rules of quantum mechanics offer a potential advantage over classical devices in terms of sensitivity. Sipahigil et al. combined the quantum optical features of silicon-vacancy color centers with diamond-based photonic cavities to form a platform for integrated quantum nanophotonics (see the Perspective by Hanson). They could thus generate single photons from the color centers, optically switch light in the cavity by addressing the state of the color center, and quantum-mechanically entangle two color centers positioned in the cavity. The work presents a viable route to develop an integrated platform for quantum networks. Science , this issue p. 847 ; see also p. 835
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Narrow-Linewidth Homogeneous Optical Emitters in Diamond Nanostructures via Silicon Ion ImplantationPhysical Review Applied 5, 044010 (2016)
@article{evans_narrow-linewidth_2016, title = {Narrow-{Linewidth} {Homogeneous} {Optical} {Emitters} in {Diamond} {Nanostructures} via {Silicon} {Ion} {Implantation}}, volume = {5}, url = {https://doi.org/10.1103/PhysRevApplied.5.044010}, doi = {10.1103/PhysRevApplied.5.044010}, journal = {Physical Review Applied}, pages = {044010}, author = {Evans, R. E. and Sipahigil, A. and Sukachev, D. D. and Zibrov, A. S. and Lukin, M. D.}, month = apr, year = {2016}, arxiv = {1512.03820} }The negatively-charged silicon-vacancy (SiV⁻) center in diamond is a bright source of indistinguishable single photons and a useful resource in quantum information protocols. Until now, SiV⁻ centers with narrow optical linewidths and small inhomogeneous distributions of SiV⁻ transition frequencies have only been reported in samples doped with silicon during diamond growth. We present a technique for producing implanted SiV⁻ centers with nearly lifetime-limited optical linewidths and a small inhomogeneous distribution. These properties persist after nanofabrication, paving the way for incorporation of high-quality SiV⁻ centers into nanophotonic devices.
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New Journal of Physics 17, 043011 (2015)
@article{jahnke_electron-phonon_2015, title = {Electron-phonon processes of the silicon-vacancy centre in diamond}, volume = {17}, url = {https://doi.org/10.1088/1367-2630/17/4/043011}, doi = {10.1088/1367-2630/17/4/043011}, journal = {New Journal of Physics}, pages = {043011}, author = {Jahnke, K. D. and Sipahigil, A. and Binder, J. M. and Doherty, M. W. and Metsch, M. and Rogers, L. J. and Manson, N. B. and Lukin, M. D. and Jelezko, F.}, month = apr, year = {2015}, arxiv = {1411.2871} }We investigate phonon induced electronic dynamics in the ground and excited states of the negatively charged silicon-vacancy (SiV⁻) centre in diamond. Optical transition line widths, transition wavelength and excited state lifetimes are measured for the temperature range 4-350 K. The ground state orbital relaxation rates are measured using time-resolved fluorescence techniques. A microscopic model of the thermal broadening in the excited and ground states of the SiV⁻ centre is developed. A vibronic process involving single-phonon transitions is found to determine orbital relaxation rates for both the ground and the excited states at cryogenic temperatures. We discuss the implications of our findings for coherence of qubit states in the ground states and propose methods to extend coherence times of SiV⁻ qubits.
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Physical Review Letters 114, 145502 (2015)
@article{goldman_phonon-induced_2015, title = {Phonon-{Induced} {Population} {Dynamics} and {Intersystem} {Crossing} in {Nitrogen}-{Vacancy} {Centers}}, volume = {114}, url = {https://doi.org/10.1103/PhysRevLett.114.145502}, doi = {10.1103/PhysRevLett.114.145502}, journal = {Physical Review Letters}, pages = {145502}, author = {Goldman, M. L. and Sipahigil, A. and Doherty, M. W. and Yao, N. Y. and Bennett, S. D. and Markham, M. and Twitchen, D. J. and Manson, N. B. and Kubanek, A. and Lukin, M. D.}, month = apr, year = {2015}, arxiv = {1406.4065} }We report direct measurement of population dynamics in the excited state manifold of a nitrogen-vacancy (NV) center in diamond. We quantify the phonon-induced mixing rate and demonstrate that it can be completely suppressed at low temperatures. Further, we measure the intersystem crossing (ISC) rate for different excited states and develop a theoretical model that unifies the phonon-induced mixing and ISC mechanisms. We find that our model is in excellent agreement with experiment and that it can be used to predict unknown elements of the NV center’s electronic structure. We discuss the model’s implications for enhancing the NV center’s performance as a room-temperature sensor.
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Physical Review B 91, 165201 (2015)
@article{goldman_state-selective_2015, title = {State-selective intersystem crossing in nitrogen-vacancy centers}, volume = {91}, url = {https://doi.org/10.1103/PhysRevB.91.165201}, doi = {10.1103/PhysRevB.91.165201}, journal = {Physical Review B}, pages = {165201}, author = {Goldman, M. L. and Doherty, M. W. and Sipahigil, A. and Yao, N. Y. and Bennett, S. D. and Manson, N. B. and Kubanek, A. and Lukin, M. D.}, month = apr, year = {2015}, arxiv = {1412.4865} }The intersystem crossing (ISC) is an important process in many solid-state atomlike impurities. For example, it allows the electronic spin state of the nitrogen-vacancy (NV) center in diamond to be initialized and read out using optical fields at ambient temperatures. This capability has enabled a wide array of applications in metrology and quantum information science. Here, we develop a microscopic model of the state-selective ISC from the optical excited state manifold of the NV center. By correlating the electron-phonon interactions that mediate the ISC with those that induce population dynamics within the NV center’s excited state manifold and those that produce the phonon sidebands of its optical transitions, we quantitatively demonstrate that our model is consistent with recent ISC measurements. Furthermore, our model constrains the unknown energy spacings between the center’s spin-singlet and spin-triplet levels. Finally, we discuss prospects to engineer the ISC in order to improve the spin initialization and readout fidelities of NV centers.
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Physical Review Letters 113, 263602 (2014)
@article{rogers_all-optical_2014, title = {All-{Optical} {Initialization}, {Readout}, and {Coherent} {Preparation} of {Single} {Silicon}-{Vacancy} {Spins} in {Diamond}}, volume = {113}, url = {https://doi.org/10.1103/PhysRevLett.113.263602}, doi = {10.1103/PhysRevLett.113.263602}, journal = {Physical Review Letters}, pages = {263602}, author = {Rogers, L. J. and Jahnke, K. D. and Metsch, M. H. and Sipahigil, A. and Binder, J. M. and Teraji, T. and Sumiya, H. and Isoya, J. and Lukin, M. D. and Hemmer, P. and Jelezko, F.}, month = dec, year = {2014}, arxiv = {1410.1355} }The silicon-vacancy (SiV⁻) color center in diamond has attracted attention due to its unique optical properties. It exhibits spectral stability and indistinguishability that facilitate efficient generation of photons capable of demonstrating quantum interference. Here we show high fidelity optical initialization and readout of electronic spin in a single SiV⁻ center with a spin relaxation time of T₁=2.4±0.2 ms. Coherent population trapping (CPT) is used to demonstrate coherent preparation of dark superposition states with a spin coherence time of T₂*=35±3 ns. This is fundamentally limited by orbital relaxation, and an understanding of this process opens the way to extend coherences by engineering interactions with phonons. These results establish the SiV⁻ center as a solid-state spin-photon interface.
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Physical Review Letters 113, 113602 (2014)
@article{sipahigil_indistinguishable_2014, title = {Indistinguishable {Photons} from {Separated} {Silicon}-{Vacancy} {Centers} in {Diamond}}, volume = {113}, url = {https://doi.org/10.1103/PhysRevLett.113.113602}, doi = {10.1103/PhysRevLett.113.113602}, journal = {Physical Review Letters}, pages = {113602}, author = {Sipahigil, A. and Jahnke, K. D. and Rogers, L. J. and Teraji, T. and Isoya, J. and Zibrov, A. S. and Jelezko, F. and Lukin, M. D.}, month = sep, year = {2014}, arxiv = {1406.4268} }We demonstrate that silicon-vacancy (SiV) centers in diamond can be used to efficiently generate coherent optical photons with excellent spectral properties. We show that these features are due to the inversion symmetry associated with SiV centers, and demonstrate generation of indistinguishable single photons from separate emitters in a Hong-Ou-Mandel (HOM) interference experiment.Prospects for realizing efficient quantum network nodes using SiV centers are discussed.
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Physical Review Letters 108, 143601 (2012)
@article{sipahigil_quantum_2012, title = {Quantum {Interference} of {Single} {Photons} from {Remote} {Nitrogen}-{Vacancy} {Centers} in {Diamond}}, volume = {108}, url = {https://doi.org/10.1103/PhysRevLett.108.143601}, doi = {10.1103/PhysRevLett.108.143601}, journal = {Physical Review Letters}, pages = {143601}, author = {Sipahigil, A. and Goldman, M. L. and Togan, E. and Chu, Y. and Markham, M. and Twitchen, D. J. and Zibrov, A. S. and Kubanek, A. and Lukin, M. D.}, month = apr, year = {2012}, arxiv = {1112.3975} }We demonstrate quantum interference between indistinguishable photons emitted by two nitrogen-vacancy (NV) centers in distinct diamond samples separated by two meters. Macroscopic solid immersion lenses are used to enhance photon collection efficiency. Quantum interference is verified by measuring a value of the second-order cross-correlation function g⁽²⁾(0) = 0.35 ± 0.04<0.5. In addition, optical transition frequencies of two separated NV centers are tuned into resonance with each other by applying external electric fields. Extension of the present approach to generate entanglement of remote solid-state qubits is discussed.
* Equal contribution
