Chris Anderson

All Publications

• Five-second coherence of a single spin with single-shot readout in silicon carbide SCIENCE ADVANCES Anderson, C. P., Glen, E. O., Zeledon, C., Bourassa, A., Jin, Y., Zhu, Y., Vorwerk, C., Crook, A. L., Abe, H., Ul-Hassan, J., Ohshima, T., Son, N. T., Galli, G., Awschalom, D. D. 2022; 8 (5): eabm5912

  Abstract

  An outstanding hurdle for defect spin qubits in silicon carbide (SiC) is single-shot readout, a deterministic measurement of the quantum state. Here, we demonstrate single-shot readout of single defects in SiC via spin-to-charge conversion, whereby the defect's spin state is mapped onto a long-lived charge state. With this technique, we achieve over 80% readout fidelity without pre- or postselection, resulting in a high signal-to-noise ratio that enables us to measure long spin coherence times. Combined with pulsed dynamical decoupling sequences in an isotopically purified host material, we report single-spin T2 > 5 seconds, over two orders of magnitude greater than previously reported in this system. The mapping of these coherent spin states onto single charges unlocks both single-shot readout for scalable quantum nodes and opportunities for electrical readout via integration with semiconductor devices.

  View details for DOI 10.1126/sciadv.abm5912

  View details for Web of Science ID 000750618100020

  View details for PubMedID 35108045

  View details for PubMedCentralID PMC8809532

• Entanglement and control of single nuclear spins in isotopically engineered silicon carbide NATURE MATERIALS Bourassa, A., Anderson, C. P., Miao, K. C., Onizhuk, M., Ma, H., Crook, A. L., Abe, H., Ul-Hassan, J., Ohshima, T., Son, N. T., Galli, G., Awschalom, D. D. 2020; 19 (12): 1319-+

  Abstract

  Nuclear spins in the solid state are both a cause of decoherence and a valuable resource for spin qubits. In this work, we demonstrate control of isolated 29Si nuclear spins in silicon carbide (SiC) to create an entangled state between an optically active divacancy spin and a strongly coupled nuclear register. We then show how isotopic engineering of SiC unlocks control of single weakly coupled nuclear spins and present an ab initio method to predict the optimal isotopic fraction that maximizes the number of usable nuclear memories. We bolster these results by reporting high-fidelity electron spin control (F = 99.984(1)%), alongside extended coherence times (Hahn-echo T2 = 2.3 ms, dynamical decoupling T2DD > 14.5 ms), and a >40-fold increase in Ramsey spin dephasing time (T2*) from isotopic purification. Overall, this work underlines the importance of controlling the nuclear environment in solid-state systems and links single photon emitters with nuclear registers in an industrially scalable material.

  View details for DOI 10.1038/s41563-020-00802-6

  View details for Web of Science ID 000571692500003

  View details for PubMedID 32958880

• Universal coherence protection in a solid-state spin qubit SCIENCE Miao, K. C., Blanton, J. P., Anderson, C. P., Bourassa, A., Crook, A. L., Wolfowicz, G., Abe, H., Ohshima, T., Awschalom, D. D. 2020; 369 (6510): 1493-+

  Abstract

  Decoherence limits the physical realization of qubits, and its mitigation is critical for the development of quantum science and technology. We construct a robust qubit embedded in a decoherence-protected subspace, obtained by applying microwave dressing to a clock transition of the ground-state electron spin of a silicon carbide divacancy defect. The qubit is universally protected from magnetic, electric, and temperature fluctuations, which account for nearly all relevant decoherence channels in the solid state. This culminates in an increase of the qubit's inhomogeneous dephasing time by more than four orders of magnitude (to >22 milliseconds), while its Hahn-echo coherence time approaches 64 milliseconds. Requiring few key platform-independent components, this result suggests that substantial coherence improvements can be achieved in a wide selection of quantum architectures.

  View details for DOI 10.1126/science.abc5186

  View details for Web of Science ID 000573904400035

  View details for PubMedID 32792463

• Electrical and optical control of single spins integrated in scalable semiconductor devices SCIENCE Anderson, C. P., Bourassa, A., Miao, K. C., Wolfowicz, G., Mintun, P. J., Crook, A. L., Abe, H., Ul Hassan, J., Son, N. T., Ohshima, T., Awschalom, D. D. 2019; 366 (6470): 1225-+

  Abstract

  Spin defects in silicon carbide have the advantage of exceptional electron spin coherence combined with a near-infrared spin-photon interface, all in a material amenable to modern semiconductor fabrication. Leveraging these advantages, we integrated highly coherent single neutral divacancy spins in commercially available p-i-n structures and fabricated diodes to modulate the local electrical environment of the defects. These devices enable deterministic charge-state control and broad Stark-shift tuning exceeding 850 gigahertz. We show that charge depletion results in a narrowing of the optical linewidths by more than 50-fold, approaching the lifetime limit. These results demonstrate a method for mitigating the ubiquitous problem of spectral diffusion in solid-state emitters by engineering the electrical environment while using classical semiconductor devices to control scalable, spin-based quantum systems.

  View details for DOI 10.1126/science.aax9406

  View details for Web of Science ID 000502662500053

  View details for PubMedID 31806809

• Quantum guidelines for solid-state spin defects NATURE REVIEWS MATERIALS Wolfowicz, G., Heremans, F., Anderson, C. P., Kanai, S., Seo, H., Gali, A., Galli, G., Awschalom, D. D. 2021; 6 (10): 906-925

  View details for DOI 10.1038/s41578-021-00306-y

  View details for Web of Science ID 000644405300003

• Probing the Coherence of Solid-State Qubits at Avoided Crossings PRX QUANTUM Onizhuk, M., Miao, K. C., Blanton, J. P., Ma, H., Anderson, C. P., Bourassa, A., Awschalom, D. D., Galli, G. 2021; 2 (1)

  View details for DOI 10.1103/PRXQuantum.2.010311

  View details for Web of Science ID 000674687500001

• Purcell Enhancement of a Single Silicon Carbide Color Center with Coherent Spin Control NANO LETTERS Crook, A. L., Anderson, C. P., Miao, K. C., Bourassa, A., Lee, H., Bayliss, S. L., Bracher, D. O., Zhang, X., Abe, H., Ohshima, T., Hu, E. L., Awschalom, D. D. 2020; 20 (5): 3427-3434

  Abstract

  Silicon carbide has recently been developed as a platform for optically addressable spin defects. In particular, the neutral divacancy in the 4H polytype displays an optically addressable spin-1 ground state and near-infrared optical emission. Here, we present the Purcell enhancement of a single neutral divacancy coupled to a photonic crystal cavity. We utilize a combination of nanolithographic techniques and a dopant-selective photoelectrochemical etch to produce suspended cavities with quality factors exceeding 5000. Subsequent coupling to a single divacancy leads to a Purcell factor of ∼50, which manifests as increased photoluminescence into the zero-phonon line and a shortened excited-state lifetime. Additionally, we measure coherent control of the divacancy ground-state spin inside the cavity nanostructure and demonstrate extended coherence through dynamical decoupling. This spin-cavity system represents an advance toward scalable long-distance entanglement protocols using silicon carbide that require the interference of indistinguishable photons from spatially separated single qubits.

  View details for DOI 10.1021/acs.nanolett.0c00339

  View details for Web of Science ID 000535255300064

  View details for PubMedID 32208710

• Developing silicon carbide for quantum spintronics APPLIED PHYSICS LETTERS Son, N. T., Anderson, C. P., Bourassa, A., Miao, K. C., Babin, C., Widmann, M., Niethammer, M., Ul Hassan, J., Morioka, N., Ivanov, I. G., Kaiser, F., Wrachtrup, J., Awschalom, D. D. 2020; 116 (19)

  View details for DOI 10.1063/5.0004454

  View details for Web of Science ID 000533502200001

• Vanadium spin qubits as telecom quantum emitters in silicon carbide SCIENCE ADVANCES Wolfowicz, G., Anderson, C. P., Diler, B., Poluektov, O. G., Heremans, F., Awschalom, D. D. 2020; 6 (18): eaaz1192

  Abstract

  Solid-state quantum emitters with spin registers are promising platforms for quantum communication, yet few emit in the narrow telecom band necessary for low-loss fiber networks. Here, we create and isolate near-surface single vanadium dopants in silicon carbide (SiC) with stable and narrow emission in the O band, with brightness allowing cavity-free detection in a wafer-scale material. In vanadium ensembles, we characterize the complex d 1 orbital physics in all five available sites in 4H-SiC and 6H-SiC. The optical transitions are sensitive to mass shifts from local silicon and carbon isotopes, enabling optically resolved nuclear spin registers. Optically detected magnetic resonance in the ground and excited orbital states reveals a variety of hyperfine interactions with the vanadium nuclear spin and clock transitions for quantum memories. Last, we demonstrate coherent quantum control of the spin state. These results provide a path for telecom emitters in the solid state for quantum applications.

  View details for DOI 10.1126/sciadv.aaz1192

  View details for Web of Science ID 000531089700019

  View details for PubMedID 32426475

  View details for PubMedCentralID PMC7195180

• Coherent control and high-fidelity readout of chromium ions in commercial silicon carbide NPJ QUANTUM INFORMATION Diler, B., Whiteley, S. J., Anderson, C. P., Wolfowicz, G., Wesson, M. E., Bielejec, E. S., Joseph Heremans, F., Awschalom, D. D. 2020; 6 (1)

  View details for DOI 10.1038/s41534-020-0247-7

  View details for Web of Science ID 000511038800001

• Electrically driven optical interferometry with spins in silicon carbide SCIENCE ADVANCES Miao, K. C., Bourassa, A., Anderson, C. P., Whiteley, S. J., Crook, A. L., Bayliss, S. L., Wolfowicz, G., Thiering, G., Udvarhelyi, P., Ivady, V., Abe, H., Ohshima, T., Gali, A., Awschalom, D. D. 2019; 5 (11): eaay0527

  Abstract

  Interfacing solid-state defect electron spins to other quantum systems is an ongoing challenge. The ground-state spin's weak coupling to its environment not only bestows excellent coherence properties but also limits desired drive fields. The excited-state orbitals of these electrons, however, can exhibit stronger coupling to phononic and electric fields. Here, we demonstrate electrically driven coherent quantum interference in the optical transition of single, basally oriented divacancies in commercially available 4H silicon carbide. By applying microwave frequency electric fields, we coherently drive the divacancy's excited-state orbitals and induce Landau-Zener-Stückelberg interference fringes in the resonant optical absorption spectrum. In addition, we find remarkably coherent optical and spin subsystems enabled by the basal divacancy's symmetry. These properties establish divacancies as strong candidates for quantum communication and hybrid system applications, where simultaneous control over optical and spin degrees of freedom is paramount.

  View details for DOI 10.1126/sciadv.aay0527

  View details for Web of Science ID 000499736100090

  View details for PubMedID 31803839

  View details for PubMedCentralID PMC6874486

• Heterodyne detection of radio-frequency electric fields using point defects in silicon carbide APPLIED PHYSICS LETTERS Wolfowicz, G., Anderson, C. P., Whiteley, S. J., Awschalom, D. D. 2019; 115 (4)

  View details for DOI 10.1063/1.5108913

  View details for Web of Science ID 000477625500019

• Spin-phonon interactions in silicon carbide addressed by Gaussian acoustics NATURE PHYSICS Whiteley, S. J., Wolfowicz, G., Anderson, C. P., Bourassa, A., Ma, H., Ye, M., Koolstra, G., Satzinger, K. J., Holt, M. V., Heremans, F., Cleland, A. N., Schuster, D. I., Galli, G., Awschalom, D. D. 2019; 15 (5): 490-+

  View details for DOI 10.1038/s41567-019-0420-0

  View details for Web of Science ID 000466716100023

• Strain annealing of SiC nanoparticles revealed through Bragg coherent diffraction imaging for quantum technologies PHYSICAL REVIEW MATERIALS Hruszkewycz, S. O., Maddali, S., Anderson, C. P., Cha, W., Miao, K. C., Highland, M. J., Ulvestad, A., Awschalom, D. D., Heremans, F. J. 2018; 2 (8)

  View details for DOI 10.1103/PhysRevMaterials.2.086001

  View details for Web of Science ID 000440636100002

• Optical charge state control of spin defects in 4H-SiC NATURE COMMUNICATIONS Wolfowicz, G., Anderson, C. P., Yeats, A. L., Whiteley, S. J., Niklas, J., Poluektov, O. G., Heremans, F., Awschalom, D. D. 2017; 8: 1876

  Abstract

  Defects in silicon carbide (SiC) have emerged as a favorable platform for optically active spin-based quantum technologies. Spin qubits exist in specific charge states of these defects, where the ability to control these states can provide enhanced spin-dependent readout and long-term charge stability. We investigate this charge state control for two major spin qubits in 4H-SiC, the divacancy and silicon vacancy, obtaining bidirectional optical charge conversion between the bright and dark states of these defects. We measure increased photoluminescence from divacancy ensembles by up to three orders of magnitude using near-ultraviolet excitation, depending on the substrate, and without degrading the electron spin coherence time. This charge conversion remains stable for hours at cryogenic temperatures, allowing spatial and persistent patterning of the charge state populations. We develop a comprehensive model of the defects and optical processes involved, offering a strong basis to improve material design and to develop quantum applications in SiC.

  View details for DOI 10.1038/s41467-017-01993-4

  View details for Web of Science ID 000416895400018

  View details for PubMedID 29192288

  View details for PubMedCentralID PMC5709515

• In situ study of annealing-induced strain relaxation in diamond nanoparticles using Bragg coherent diffraction imaging APL MATERIALS Hruszkewycz, S. O., Cha, W., Andrich, P., Anderson, C. P., Ulvestad, A., Harder, R., Fuoss, P. H., Awschalom, D. D., Heremans, F. J. 2017; 5 (2)

  View details for DOI 10.1063/1.4974865

  View details for Web of Science ID 000395031400005

• Solvent dependent branching between C-I and C-Br bond cleavage following 266 nm excitation of CH2BrI JOURNAL OF CHEMICAL PHYSICS Anderson, C. P., Spears, K. G., Wilson, K. R., Sension, R. J. 2013; 139 (19): 194307

  Abstract

  It is well known that ultraviolet photoexcitation of halomethanes results in halogen-carbon bond cleavage. Each halogen-carbon bond has a dominant ultraviolet (UV) absorption that promotes an electron from a nonbonding halogen orbital (nX) to a carbon-halogen antibonding orbital (σ*C-X). UV absorption into specific transitions in the gas phase results primarily in selective cleavage of the corresponding carbon-halogen bond. In the present work, broadband ultrafast UV-visible transient absorption studies of CH2BrI reveal a more complex photochemistry in solution. Transient absorption spectra are reported spanning the range from 275 nm to 750 nm and 300 fs to 3 ns following excitation of CH2BrI at 266 nm in acetonitrile, 2-butanol, and cyclohexane. Channels involving formation of CH2Br + I radical pairs, iso-CH2Br-I, and iso-CH2I-Br are identified. The solvent environment has a significant influence on the branching ratios, and on the formation and stability of iso-CH2Br-I. Both iso-CH2Br-I and iso-CH2I-Br are observed in cyclohexane with a ratio of ~2.8:1. In acetonitrile this ratio is 7:1 or larger. The observation of formation of iso-CH2I-Br photoproduct as well as iso-CH2Br-I following 266 nm excitation is a novel result that suggests complexity in the dissociation mechanism. We also report a solvent and concentration dependent lifetime of iso-CH2Br-I. At low concentrations the lifetime is >4 ns in acetonitrile, 1.9 ns in 2-butanol and ~1.4 ns in cyclohexane. These lifetimes decrease with higher initial concentrations of CH2BrI. The concentration dependence highlights the role that intermolecular interactions can play in the quenching of unstable isomers of dihalomethanes.

  View details for DOI 10.1063/1.4829899

  View details for Web of Science ID 000327714900020

  View details for PubMedID 24320326

• Carrier-envelope phase-and spectral control of fractional high-harmonic combs JOURNAL OF APPLIED PHYSICS Raith, P., Ott, C., Meyer, K., Kaldun, A., Laux, M., Ceci, M., Anderson, C. P., Pfeifer, T. 2013; 114 (17)

  View details for DOI 10.1063/1.4827194

  View details for Web of Science ID 000327591900003

• Fractional high-harmonic combs by attosecond-precision split-spectrum pulse control Raith, P., Ott, C., Anderson, C. P., Kaldun, A., Meyer, K., Laux, M., Zhang, Y., Pfeifer, T., Chergui, M., Taylor, A., Cundiff, S., DeVivieRiedle, R., Yamagouchi, K. E D P SCIENCES. 2013

  View details for DOI 10.1051/epjconf/20134101007

  View details for Web of Science ID 000320558600007

• Fractional high-order harmonic combs and energy tuning by attosecond-precision split-spectrum pulse control APPLIED PHYSICS LETTERS Raith, P., Ott, C., Anderson, C. P., Kaldun, A., Meyer, K., Laux, M., Zhang, Y., Pfeifer, T. 2012; 100 (12)

  View details for DOI 10.1063/1.3693615

  View details for Web of Science ID 000302228700004

• Fractional high-order harmonic combs and energy tuning by split-spectrum field synthesis Raith, P., Ott, C., Anderson, C. P., Kaldun, A., Meyer, K., Laux, M., Zhang, Y., Pfeifer, T., IEEE IEEE. 2012

  View details for Web of Science ID 000310362403235

• A Large-Scale Complex Haploinsufficiency-Based Genetic Interaction Screen in Candida albicans: Analysis of the RAM Network during Morphogenesis PLOS GENETICS Bharucha, N., Chabrier-Rosello, Y., Xu, T., Johnson, C., Sobczynski, S., Song, Q., Dobry, C. J., Eckwahl, M. J., Anderson, C. P., Benjamin, A. J., Kumar, A., Krysan, D. J. 2011; 7 (4): e1002058

  Abstract

  The morphogenetic transition between yeast and filamentous forms of the human fungal pathogen Candida albicans is regulated by a variety of signaling pathways. How these pathways interact to orchestrate morphogenesis, however, has not been as well characterized. To address this question and to identify genes that interact with the Regulation of Ace2 and Morphogenesis (RAM) pathway during filamentation, we report the first large-scale genetic interaction screen in C. albicans.Our strategy for this screen was based on the concept of complex haploinsufficiency (CHI). A heterozygous mutant of CBK1(cbk1Δ/CBK1), a key RAM pathway protein kinase, was subjected to transposon-mediated, insertional mutagenesis. The resulting double heterozygous mutants (6,528 independent strains) were screened for decreased filamentation on SpiderMedium (SM). From the 441 mutants showing altered filamentation, 139 transposon insertion sites were sequenced,yielding 41 unique CBK1-interacting genes. This gene set was enriched in transcriptional targets of Ace2 and, strikingly, the cAMP-dependent protein kinase A (PKA) pathway, suggesting an interaction between these two pathways. Further analysis indicates that the RAM and PKA pathways co-regulate a common set of genes during morphogenesis and that hyperactivation of the PKA pathway may compensate for loss of RAM pathway function. Our data also indicate that the PKA–regulated transcription factor Efg1 primarily localizes to yeast phase cells while the RAM–pathway regulated transcription factor Ace2 localizes to daughter nuclei of filamentous cells, suggesting that Efg1 and Ace2 regulate a common set of genes at separate stages of morphogenesis. Taken together, our observations indicate that CHI–based screening is a useful approach to genetic interaction analysis in C. albicans and support a model in which these two pathways regulate a common set of genes at different stages of filamentation.

  View details for DOI 10.1371/journal.pgen.1002058

  View details for Web of Science ID 000289977000002

  View details for PubMedID 22103005

  View details for PubMedCentralID PMC3084211