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Sathyamoorthy SR, Tornberg L, Kockum AF, Baragiola BQ, Combes J, Wilson CM, Stace TM, Johansson G. Quantum nondemolition detection of a propagating microwave photon. Phys Rev Lett 2014; 112:093601. [PMID: 24655250 DOI: 10.1103/physrevlett.112.093601] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Indexed: 05/27/2023]
Abstract
The ability to nondestructively detect the presence of a single, traveling photon has been a long-standing goal in optics, with applications in quantum information and measurement. Realizing such a detector is complicated by the fact that photon-photon interactions are typically very weak. At microwave frequencies, very strong effective photon-photon interactions in a waveguide have recently been demonstrated. Here we show how this type of interaction can be used to realize a quantum nondemolition measurement of a single propagating microwave photon. The scheme we propose uses a chain of solid-state three-level systems (transmons) cascaded through circulators which suppress photon backscattering. Our theoretical analysis shows that microwave-photon detection with fidelity around 90% can be realized with existing technologies.
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Affiliation(s)
- Sankar R Sathyamoorthy
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden
| | - L Tornberg
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden
| | - Anton F Kockum
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden
| | - Ben Q Baragiola
- Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA
| | - Joshua Combes
- Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA
| | - C M Wilson
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden and Institute for Quantum Computing and Electrical and Computer Engineering Department, University of Waterloo, Waterloo N2 L 3G1, Canada
| | - Thomas M Stace
- Centre for Engineered Quantum Systems, School of Physical Sciences, University of Queensland, Saint Lucia, Queensland 4072, Australia
| | - G Johansson
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, S-41296 Gothenburg, Sweden
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Groen JP, Ristè D, Tornberg L, Cramer J, de Groot PC, Picot T, Johansson G, DiCarlo L. Partial-measurement backaction and nonclassical weak values in a superconducting circuit. Phys Rev Lett 2013; 111:090506. [PMID: 24033014 DOI: 10.1103/physrevlett.111.090506] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 06/29/2013] [Indexed: 06/02/2023]
Abstract
We realize indirect partial measurement of a transmon qubit in circuit quantum electrodynamics by interaction with an ancilla qubit and projective ancilla measurement with a dedicated readout resonator. Accurate control of the interaction and ancilla measurement basis allows tailoring the measurement strength and operator. The tradeoff between measurement strength and qubit backaction is characterized through the distortion of a qubit Rabi oscillation imposed by ancilla measurement in different bases. Combining partial and projective qubit measurements, we provide the solid-state demonstration of the correspondence between a nonclassical weak value and the violation of a Leggett-Garg inequality.
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Affiliation(s)
- J P Groen
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
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Chow JM, Gambetta JM, Tornberg L, Koch J, Bishop LS, Houck AA, Johnson BR, Frunzio L, Girvin SM, Schoelkopf RJ. Randomized benchmarking and process tomography for gate errors in a solid-state qubit. Phys Rev Lett 2009; 102:090502. [PMID: 19392502 DOI: 10.1103/physrevlett.102.090502] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Indexed: 05/27/2023]
Abstract
We present measurements of single-qubit gate errors for a superconducting qubit. Results from quantum process tomography and randomized benchmarking are compared with gate errors obtained from a double pi pulse experiment. Randomized benchmarking reveals a minimum average gate error of 1.1+/-0.3% and a simple exponential dependence of fidelity on the number of gates. It shows that the limits on gate fidelity are primarily imposed by qubit decoherence, in agreement with theory.
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Affiliation(s)
- J M Chow
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
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