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Liu CH, Harrison DC, Patel S, Wilen CD, Rafferty O, Shearrow A, Ballard A, Iaia V, Ku J, Plourde BLT, McDermott R. Quasiparticle Poisoning of Superconducting Qubits from Resonant Absorption of Pair-Breaking Photons. Phys Rev Lett 2024; 132:017001. [PMID: 38242669 DOI: 10.1103/physrevlett.132.017001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 11/22/2023] [Accepted: 11/29/2023] [Indexed: 01/21/2024]
Abstract
The ideal superconductor provides a pristine environment for the delicate states of a quantum computer: because there is an energy gap to excitations, there are no spurious modes with which the qubits can interact, causing irreversible decay of the quantum state. As a practical matter, however, there exists a high density of excitations out of the superconducting ground state even at ultralow temperature; these are known as quasiparticles. Observed quasiparticle densities are of order 1 μm^{-3}, tens of orders of magnitude greater than the equilibrium density expected from theory. Nonequilibrium quasiparticles extract energy from the qubit mode and can induce dephasing. Here we show that a dominant mechanism for quasiparticle poisoning is direct absorption of high-energy photons at the qubit junction. We use a Josephson junction-based photon source to controllably dose qubit circuits with millimeter-wave radiation, and we use an interferometric quantum gate sequence to reconstruct the charge parity of the qubit. We find that the structure of the qubit itself acts as a resonant antenna for millimeter-wave radiation, providing an efficient path for photons to generate quasiparticles. A deep understanding of this physics will pave the way to realization of next-generation superconducting qubits that are robust against quasiparticle poisoning.
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Affiliation(s)
- C H Liu
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - D C Harrison
- Intelligence Community Postdoctoral Research Fellowship Program, Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S Patel
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - C D Wilen
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - O Rafferty
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A Shearrow
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A Ballard
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - V Iaia
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - J Ku
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - B L T Plourde
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - R McDermott
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Dodge K, Liu Y, Klots AR, Cole B, Shearrow A, Senatore M, Zhu S, Ioffe LB, McDermott R, Plourde BLT. Hardware Implementation of Quantum Stabilizers in Superconducting Circuits. Phys Rev Lett 2023; 131:150602. [PMID: 37897769 DOI: 10.1103/physrevlett.131.150602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 09/07/2023] [Indexed: 10/30/2023]
Abstract
Stabilizer operations are at the heart of quantum error correction and are typically implemented in software-controlled entangling gates and measurements of groups of qubits. Alternatively, qubits can be designed so that the Hamiltonian corresponds directly to a stabilizer for protecting quantum information. We demonstrate such a hardware implementation of stabilizers in a superconducting circuit composed of chains of π-periodic Josephson elements. With local on-chip flux and charge biasing, we observe a progressive softening of the energy band dispersion with respect to flux as the number of frustrated plaquette elements is increased, in close agreement with our numerical modeling.
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Affiliation(s)
- K Dodge
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - Y Liu
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - A R Klots
- Google Quantum AI, Santa Barbara, California 93111, USA
| | - B Cole
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - A Shearrow
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M Senatore
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - S Zhu
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - L B Ioffe
- Google Quantum AI, Santa Barbara, California 93111, USA
| | - R McDermott
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - B L T Plourde
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
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Ku J, Xu X, Brink M, McKay DC, Hertzberg JB, Ansari MH, Plourde BLT. Suppression of Unwanted ZZ Interactions in a Hybrid Two-Qubit System. Phys Rev Lett 2020; 125:200504. [PMID: 33258640 DOI: 10.1103/physrevlett.125.200504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 09/02/2020] [Indexed: 06/12/2023]
Abstract
Mitigating crosstalk errors, whether classical or quantum mechanical, is critically important for achieving high-fidelity entangling gates in multiqubit circuits. For weakly anharmonic superconducting qubits, unwanted ZZ interactions can be suppressed by combining qubits with opposite anharmonicity. We present experimental measurements and theoretical modeling of two-qubit gate error for gates based on the cross resonance interaction between a capacitively shunted flux qubit and a transmon, and demonstrate the elimination of the ZZ interaction.
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Affiliation(s)
- Jaseung Ku
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - Xuexin Xu
- Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52428, Germany
- Jülich-Aachen Research Alliance (JARA), Fundamentals of Future Information Technologies, Jülich 52428, Germany
| | - Markus Brink
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - David C McKay
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Jared B Hertzberg
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Mohammad H Ansari
- Peter Grünberg Institute, Forschungszentrum Jülich, Jülich 52428, Germany
- Jülich-Aachen Research Alliance (JARA), Fundamentals of Future Information Technologies, Jülich 52428, Germany
| | - B L T Plourde
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
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Opremcak A, Pechenezhskiy IV, Howington C, Christensen BG, Beck MA, Leonard E, Suttle J, Wilen C, Nesterov KN, Ribeill GJ, Thorbeck T, Schlenker F, Vavilov MG, Plourde BLT, McDermott R. Measurement of a superconducting qubit with a microwave photon counter. Science 2018; 361:1239-1242. [DOI: 10.1126/science.aat4625] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 07/17/2018] [Indexed: 11/02/2022]
Affiliation(s)
- A. Opremcak
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - I. V. Pechenezhskiy
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - C. Howington
- Department of Physics, Syracuse University, Syracuse, NY 13244, USA
| | - B. G. Christensen
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - M. A. Beck
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - E. Leonard
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - J. Suttle
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - C. Wilen
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - K. N. Nesterov
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - G. J. Ribeill
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - T. Thorbeck
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - F. Schlenker
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - M. G. Vavilov
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - B. L. T. Plourde
- Department of Physics, Syracuse University, Syracuse, NY 13244, USA
| | - R. McDermott
- Department of Physics, University of Wisconsin–Madison, Madison, WI 53706, USA
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Paik H, Mezzacapo A, Sandberg M, McClure DT, Abdo B, Córcoles AD, Dial O, Bogorin DF, Plourde BLT, Steffen M, Cross AW, Gambetta JM, Chow JM. Experimental Demonstration of a Resonator-Induced Phase Gate in a Multiqubit Circuit-QED System. Phys Rev Lett 2016; 117:250502. [PMID: 28036205 DOI: 10.1103/physrevlett.117.250502] [Citation(s) in RCA: 7] [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: 06/06/2016] [Indexed: 06/06/2023]
Abstract
The resonator-induced phase (RIP) gate is an all-microwave multiqubit entangling gate that allows a high degree of flexibility in qubit frequencies, making it attractive for quantum operations in large-scale architectures. We experimentally realize the RIP gate with four superconducting qubits in a three-dimensional circuit-QED architecture, demonstrating high-fidelity controlled-z (cz) gates between all possible pairs of qubits from two different 4-qubit devices in pair subspaces. These qubits are arranged within a wide range of frequency detunings, up to as large as 1.8 GHz. We further show a dynamical multiqubit refocusing scheme in order to isolate out 2-qubit interactions, and combine them to generate a 4-qubit Greenberger-Horne-Zeilinger state.
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Affiliation(s)
- Hanhee Paik
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - A Mezzacapo
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - Martin Sandberg
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - D T McClure
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - B Abdo
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - A D Córcoles
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - O Dial
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - D F Bogorin
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - B L T Plourde
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - M Steffen
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - A W Cross
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - J M Gambetta
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
| | - Jerry M Chow
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598-0218, USA
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Nsanzineza I, Plourde BLT. Trapping a single vortex and reducing quasiparticles in a superconducting resonator. Phys Rev Lett 2014; 113:117002. [PMID: 25260000 DOI: 10.1103/physrevlett.113.117002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Indexed: 06/03/2023]
Abstract
Vortices trapped in thin-film superconducting microwave resonators can have a significant influence on the resonator performance. Using a variable-linewidth geometry for a weakly coupled resonator, we are able to observe the effects of a single vortex trapped in the resonator through field cooling. For resonant modes where the vortex is near a current antinode, the presence of even a single vortex leads to a measurable decrease in the quality factor and a dispersive shift of the resonant frequency. For modes with the vortex located at a current node, the presence of the vortex results in no detectable excess loss and, in fact, produces an increase in the quality factor. We attribute this enhancement to a reduction in the density of nonequilibrium quasiparticles in the resonator due to their trapping and relaxation near the vortex core.
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Affiliation(s)
- I Nsanzineza
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| | - B L T Plourde
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
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Heitmann TW, Yu K, Song C, DeFeo MP, Plourde BLT, Hesselberth MBS, Kes PH. Picovoltmeter for probing vortex dynamics in a single weak-pinning Corbino channel. Rev Sci Instrum 2008; 79:103906. [PMID: 19044728 DOI: 10.1063/1.3000683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have developed a picovoltmeter using a Nb dc superconducting quantum interference device for measuring the flux-flow voltage from a small number of vortices moving through a submicron weak-pinning superconducting channel. We have applied this picovoltmeter to measure the vortex response in a single channel arranged in a circle on a Corbino disk geometry. The circular channel allows the vortices to follow closed orbits without encountering any sample edges, thus eliminating the influence of entry barriers.
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Affiliation(s)
- T W Heitmann
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
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Abstract
The ability to switch the coupling between quantum bits (qubits) on and off is essential for implementing many quantum-computing algorithms. We demonstrated such control with two flux qubits coupled together through their mutual inductances and through the dc superconducting quantum interference device (SQUID) that reads out their magnetic flux states. A bias current applied to the SQUID in the zero-voltage state induced a change in the dynamic inductance, reducing the coupling energy controllably to zero and reversing its sign.
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Affiliation(s)
- T Hime
- Department of Physics, University of California, Berkeley, CA 94720-7300, USA
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