1
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Wei KX, Magesan E, Lauer I, Srinivasan S, Bogorin DF, Carnevale S, Keefe GA, Kim Y, Klaus D, Landers W, Sundaresan N, Wang C, Zhang EJ, Steffen M, Dial OE, McKay DC, Kandala A. Hamiltonian Engineering with Multicolor Drives for Fast Entangling Gates and Quantum Crosstalk Cancellation. Phys Rev Lett 2022; 129:060501. [PMID: 36018659 DOI: 10.1103/physrevlett.129.060501] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Quantum computers built with superconducting artificial atoms already stretch the limits of their classical counterparts. While the lowest energy states of these artificial atoms serve as the qubit basis, the higher levels are responsible for both a host of attractive gate schemes as well as generating undesired interactions. In particular, when coupling these atoms to generate entanglement, the higher levels cause shifts in the computational levels that lead to unwanted ZZ quantum crosstalk. Here, we present a novel technique to manipulate the energy levels and mitigate this crosstalk with simultaneous off-resonant drives on coupled qubits. This breaks a fundamental deadlock between qubit-qubit coupling and crosstalk. In a fixed-frequency transmon architecture with strong coupling and crosstalk cancellation, additional cross-resonance drives enable a 90 ns CNOT with a gate error of (0.19±0.02)%, while a second set of off-resonant drives enables a novel CZ gate. Furthermore, we show a definitive improvement in circuit performance with crosstalk cancellation over seven qubits, demonstrating the scalability of the technique. This Letter paves the way for superconducting hardware with faster gates and greatly improved multiqubit circuit fidelities.
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Affiliation(s)
- K X Wei
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - E Magesan
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - I Lauer
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - S Srinivasan
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - D F Bogorin
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - S Carnevale
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - G A Keefe
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Y Kim
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - D Klaus
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - W Landers
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - N Sundaresan
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - C Wang
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - E J Zhang
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - M Steffen
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - O E Dial
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - D C McKay
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - A Kandala
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
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2
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Zhang EJ, Srinivasan S, Sundaresan N, Bogorin DF, Martin Y, Hertzberg JB, Timmerwilke J, Pritchett EJ, Yau JB, Wang C, Landers W, Lewandowski EP, Narasgond A, Rosenblatt S, Keefe GA, Lauer I, Rothwell MB, McClure DT, Dial OE, Orcutt JS, Brink M, Chow JM. High-performance superconducting quantum processors via laser annealing of transmon qubits. Sci Adv 2022; 8:eabi6690. [PMID: 35559683 PMCID: PMC9106287 DOI: 10.1126/sciadv.abi6690] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 03/31/2022] [Indexed: 06/15/2023]
Abstract
Scaling the number of qubits while maintaining high-fidelity quantum gates remains a key challenge for quantum computing. Presently, superconducting quantum processors with >50 qubits are actively available. For these systems, fixed-frequency transmons are attractive because of their long coherence and noise immunity. However, scaling fixed-frequency architectures proves challenging because of precise relative frequency requirements. Here, we use laser annealing to selectively tune transmon qubits into desired frequency patterns. Statistics over hundreds of annealed qubits demonstrate an empirical tuning precision of 18.5 MHz, with no measurable impact on qubit coherence. We quantify gate error statistics on a tuned 65-qubit processor, with median two-qubit gate fidelity of 98.7%. Baseline tuning statistics yield a frequency-equivalent resistance precision of 4.7 MHz, sufficient for high-yield scaling beyond 103 qubit levels. Moving forward, we anticipate selective laser annealing to play a central role in scaling fixed-frequency architectures.
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3
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Kandala A, Wei KX, Srinivasan S, Magesan E, Carnevale S, Keefe GA, Klaus D, Dial O, McKay DC. Demonstration of a High-Fidelity cnot Gate for Fixed-Frequency Transmons with Engineered ZZ Suppression. Phys Rev Lett 2021; 127:130501. [PMID: 34623861 DOI: 10.1103/physrevlett.127.130501] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 07/28/2021] [Indexed: 06/13/2023]
Abstract
Improving two-qubit gate performance and suppressing cross talk are major, but often competing, challenges to achieving scalable quantum computation. In particular, increasing the coupling to realize faster gates has been intrinsically linked to enhanced cross talk due to unwanted two-qubit terms in the Hamiltonian. Here, we demonstrate a novel coupling architecture for transmon qubits that circumvents the standard relationship between desired and undesired interaction rates. Using two fixed frequency coupling elements to tune the dressed level spacings, we demonstrate an intrinsic suppression of the static ZZ while maintaining large effective coupling rates. Our architecture reveals no observable degradation of qubit coherence (T_{1},T_{2}>100 μs) and, over a factor of 6 improvement in the ratio of desired to undesired coupling. Using the cross-resonance interaction, we demonstrate a 180 ns single-pulse controlled not (cnot) gate, and measure a cnot fidelity of 99.77(2)% from interleaved randomized benchmarking.
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Affiliation(s)
- A Kandala
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - K X Wei
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - S Srinivasan
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - E Magesan
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - S Carnevale
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - G A Keefe
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - D Klaus
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - O Dial
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - D C McKay
- IBM Quantum, IBM T.J. Watson Research Center, Yorktown Heights, New York 10598, USA
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4
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Stehlik J, Zajac DM, Underwood DL, Phung T, Blair J, Carnevale S, Klaus D, Keefe GA, Carniol A, Kumph M, Steffen M, Dial OE. Tunable Coupling Architecture for Fixed-Frequency Transmon Superconducting Qubits. Phys Rev Lett 2021; 127:080505. [PMID: 34477428 DOI: 10.1103/physrevlett.127.080505] [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: 01/24/2021] [Accepted: 07/19/2021] [Indexed: 06/13/2023]
Abstract
Implementation of high-fidelity 2-qubit operations is a key ingredient for scalable quantum error correction. In superconducting qubit architectures, tunable buses have been explored as a means to higher-fidelity gates. However, these buses introduce new pathways for leakage. Here we present a modified tunable bus architecture appropriate for fixed-frequency qubits in which the adiabaticity restrictions on gate speed are reduced. We characterize this coupler on a range of 2-qubit devices, achieving a maximum gate fidelity of 99.85%. We further show the calibration is stable over one day.
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Affiliation(s)
- J Stehlik
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - D M Zajac
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - D L Underwood
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - T Phung
- IBM Quantum, IBM Almaden Research Center, San Jose, California 95120, USA
| | - J Blair
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - S Carnevale
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - D Klaus
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - G A Keefe
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - A Carniol
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - M Kumph
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Matthias Steffen
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - O E Dial
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
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5
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Poletto S, Gambetta JM, Merkel ST, Smolin JA, Chow JM, Córcoles AD, Keefe GA, Rothwell MB, Rozen JR, Abraham DW, Rigetti C, Steffen M. Entanglement of two superconducting qubits in a waveguide cavity via monochromatic two-photon excitation. Phys Rev Lett 2012; 109:240505. [PMID: 23368296 DOI: 10.1103/physrevlett.109.240505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Indexed: 06/01/2023]
Abstract
We report a system where fixed interactions between noncomputational levels make bright the otherwise forbidden two-photon |00}→|11} transition. The system is formed by hand selection and assembly of two discrete component transmon-style superconducting qubits inside a rectangular microwave cavity. The application of a monochromatic drive tuned to this transition induces two-photon Rabi-like oscillations between the ground and doubly excited states via the Bell basis. The system therefore allows all-microwave two-qubit universal control with the same techniques and hardware required for single qubit control. We report Ramsey-like and spin echo sequences with the generated Bell states, and measure a two-qubit gate fidelity of F(g)=90% (unconstrained) and 86% (maximum likelihood estimator).
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Affiliation(s)
- S Poletto
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA
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6
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Magesan E, Gambetta JM, Johnson BR, Ryan CA, Chow JM, Merkel ST, da Silva MP, Keefe GA, Rothwell MB, Ohki TA, Ketchen MB, Steffen M. Efficient measurement of quantum gate error by interleaved randomized benchmarking. Phys Rev Lett 2012; 109:080505. [PMID: 23002731 DOI: 10.1103/physrevlett.109.080505] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Indexed: 06/01/2023]
Abstract
We describe a scalable experimental protocol for estimating the average error of individual quantum computational gates. This protocol consists of interleaving random Clifford gates between the gate of interest and provides an estimate as well as theoretical bounds for the average error of the gate under test, so long as the average noise variation over all Clifford gates is small. This technique takes into account both state preparation and measurement errors and is scalable in the number of qubits. We apply this protocol to a superconducting qubit system and find a bounded average error of 0.003 [0,0.016] for the single-qubit gates X(π/2) and Y(π/2). These bounded values provide better estimates of the average error than those extracted via quantum process tomography.
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Affiliation(s)
- Easwar Magesan
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
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7
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Chow JM, Gambetta JM, Córcoles AD, Merkel ST, Smolin JA, Rigetti C, Poletto S, Keefe GA, Rothwell MB, Rozen JR, Ketchen MB, Steffen M. Universal quantum gate set approaching fault-tolerant thresholds with superconducting qubits. Phys Rev Lett 2012; 109:060501. [PMID: 23006254 DOI: 10.1103/physrevlett.109.060501] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Indexed: 06/01/2023]
Abstract
We use quantum process tomography to characterize a full universal set of all-microwave gates on two superconducting single-frequency single-junction transmon qubits. All extracted gate fidelities, including those for Clifford group generators, single-qubit π/4 and π/8 rotations, and a two-qubit controlled-not, exceed 95% (98%), without (with) subtracting state preparation and measurement errors. Furthermore, we introduce a process map representation in the Pauli basis which is visually efficient and informative. This high-fidelity gate set serves as a critical building block towards scalable architectures of superconducting qubits for error correction schemes and pushes up on the known limits of quantum gate characterization.
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Affiliation(s)
- Jerry M Chow
- IBM TJ Watson Research Center, Yorktown Heights, New York 10598, USA
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8
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Chow JM, Córcoles AD, Gambetta JM, Rigetti C, Johnson BR, Smolin JA, Rozen JR, Keefe GA, Rothwell MB, Ketchen MB, Steffen M. Simple all-microwave entangling gate for fixed-frequency superconducting qubits. Phys Rev Lett 2011; 107:080502. [PMID: 21929152 DOI: 10.1103/physrevlett.107.080502] [Citation(s) in RCA: 12] [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: 06/02/2011] [Indexed: 05/31/2023]
Abstract
We demonstrate an all-microwave two-qubit gate on superconducting qubits which are fixed in frequency at optimal bias points. The gate requires no additional subcircuitry and is tunable via the amplitude of microwave irradiation on one qubit at the transition frequency of the other. We use the gate to generate entangled states with a maximal extracted concurrence of 0.88, and quantum process tomography reveals a gate fidelity of 81%.
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Affiliation(s)
- Jerry M Chow
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
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9
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Steffen M, Kumar S, Divincenzo DP, Rozen JR, Keefe GA, Rothwell MB, Ketchen MB. High-coherence hybrid superconducting qubit. Phys Rev Lett 2010; 105:100502. [PMID: 20867498 DOI: 10.1103/physrevlett.105.100502] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Indexed: 05/27/2023]
Abstract
We report quantum coherence measurements of a superconducting qubit whose design is a hybrid of several existing types. Excellent coherence times are found: T2∼T1∼1.5 μs. The topology of the qubit is that of a traditional three-junction flux qubit, but it has a large shunting capacitance, and the ratio of the junction critical currents is chosen so that the qubit potential has a single-well form. The qubit has a sizable nonlinearity, but its sign is reversed compared with most other popular qubit designs. The qubit is read out dispersively using a high-Q resonator in a λ/2 configuration.
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Affiliation(s)
- Matthias Steffen
- IBM Watson Research Center, Yorktown Heights, New York 10598, USA
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10
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Abstract
We have fabricated several 50 omega characteristic impedance low-pass metal powder filters. The filters are made with bronze or copper metal powder with varying amounts of metal powder in a metal powder/epoxy mixture. Our goal is to make a filter with a characteristic impedance Z = 50 omega at frequencies up to 10 GHz. Using a 78% bronze powder/epoxy mixture in a suitable geometry, we achieved an impedance Z = 54 omega at 4.2 K, with a cutoff frequency fc approximately/= 0.3 GHz and an attenuation A = Vout/Vin=0.0001 (-80 dB) at 10 GHz. We also made several non-50 omega low-pass bronze powder filters with fc = 1 MHz and A = 0.0001 at 10 MHz. Fabrication details and performance data will be presented for both types of filter.
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Affiliation(s)
- F P Milliken
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, USA.
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11
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Koch RH, Keefe GA, Milliken FP, Rozen JR, Tsuei CC, Kirtley JR, DiVincenzo DP. Experimental demonstration of an oscillator stabilized Josephson flux qubit. Phys Rev Lett 2006; 96:127001. [PMID: 16605945 DOI: 10.1103/physrevlett.96.127001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Indexed: 05/08/2023]
Abstract
We experimentally demonstrate the use of a superconducting transmission line, shorted at both ends, to stabilize the operation of a tunable flux qubit. Using harmonic-oscillator stabilization and pulsed dc operation, we have observed Larmor oscillations with a single shot visibility of 90%. In another qubit, the visibility was 60% and there was no measurable visibility reduction after 35 ns.
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Affiliation(s)
- R H Koch
- IBM Watson Research Center, Yorktown Heights, New York 10598, USA
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12
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Koch RH, Grinstein G, Keefe GA, Lu Y, Trouilloud PL, Gallagher WJ, Parkin SS. Thermally assisted magnetization reversal in submicron-sized magnetic thin films. Phys Rev Lett 2000; 84:5419-5422. [PMID: 10990958 DOI: 10.1103/physrevlett.84.5419] [Citation(s) in RCA: 9] [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: 12/27/1999] [Indexed: 05/23/2023]
Abstract
We have measured the rate of thermally assisted magnetization reversal of submicron-sized magnetic thin films. For fields H just less than the zero-temperature switching field H(C), the probability of reversal, P(exp)(s)(t), increases for short times t, achieves a maximum value, and then decreases exponentially. Micromagnetic simulations exhibit the same behavior and show that the reversal proceeds through the annihilation of two domain walls that move from opposite sides of the sample. The behavior of P(exp)(s)(t) can be understood through a simple "energy-ladder" model of thermal activation.
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Affiliation(s)
- RH Koch
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, USA
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