Continuous-variable geometric phase and its manipulation for quantum computation in a superconducting circuit

Song, Cunxian; Zheng, Shi‐Biao; Zhang, Pengfei; Xu, Kai; Zhang, Libo; Guo, Qiujiang; Liu, Wuxin; Xu, Da; Deng, Hui; Huang, Keqiang; Zheng, Di; Zhu, Xiaobo; Wang, H.

doi:10.1038/s41467-017-01156-5

Cited by 90 publications

(67 citation statements)

References 41 publications

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“…38 Finding high quality control pulses and improving complex multi-qubits gates under experimental conditions remains challenging, as evidenced by continued research in this field. 21,36 We believe that nonadiabatic detuning can be a powerful method 21,26,27,36 for two-and three-qubits gates. The errors in the simulated gates are of the same order of magnitude as the errors from incoherent errors; additionally, the gate time is acceptably short (78.5 ns, 1.73/(2g 01,10 )).…”

Section: Discussionmentioning

confidence: 99%

“…Motivated by the quest for quantum error correction and expanding the set of realisable circuits, 1,2 there has been a great effort to improve the design of entangling gates, [1][2][3][4][5][6][7][8][9][10][11] and by now there is a rich array of design choices in a variety of quantum computing modalities, including superconducting quantum circuits, 12 trapped ions, 13 quantum dots 14 and NV diamonds. 15,16 Notable designs for entangling gates in superconducting circuits, include fast adiabatic gates, 17 frequency modulation, 11,18 cross resonance 19,20 and resonator-induced phase, 21,22 which effect the gates using longitudinal (first two) or transverse (last two) control of the qubits. Currently, the best results for entangling-gate fidelity using longitudinal control is 99.44%, 3 and using transverse control is 99.1%.…”

Section: Introductionmentioning

confidence: 99%

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Realisation of high-fidelity nonadiabatic CZ gates with superconducting qubits

Castellano

Wang

et al. 2019

npj Quantum Inf

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Entangling gates with error rates reaching the threshold for quantum error correction have been reported for CZ gates using adiabatic longitudinal control based on the interaction between the |11〉 and |20〉 states. Here, we design and implement nonadiabatic CZ gates, which outperform adiabatic gates in terms of speed and fidelity, with gate times reaching 1:25=ð2 ffiffi ffi 2 p g 01;10 Þ, and fidelities reaching 99.54 ± 0.08%. Nonadiabatic gates are found to have proportionally less incoherent error than adiabatic gates thanks to their fast gate times, which leave more room for further improvements in the design of the control pules to eliminate coherent errors. We also show that state leakage can be reduced to below 0.2% with optimisation. Furthermore, the gate optimisation process is highly feasible: experimental optimisation can be expected to take less than four hours. Finally, the gate design process can be extended to CCZ gates, and our preliminary results suggest that this process would be feasible as well, if we can measure the CCZ fidelity separate from the initialisation and readout errors in experimental optimisation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Realisation of high-fidelity nonadiabatic CZ gates with superconducting qubits

Castellano

Wang

et al. 2019

npj Quantum Inf

Self Cite

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“…The optimization procedure will converge once the constraint (7) has been satisfied and the improvement in ϕ µν (τ g ) between successive iterations drops below a set threshold, chosen to be 10 −4 . A maximally entangling gate may be successfully achieved if ϕ µν (τ g ) ≥ π/8.…”

Section: Maximum-likelihood Procedures For State Estimationmentioning

confidence: 99%

Phase-Modulated Entangling Gates Robust to Static and Time-Varying Errors

et al. 2020

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Entangling operations are among the most important primitive gates employed in quantum computing and it is crucial to ensure high-fidelity implementations as systems are scaled up. We experimentally realize and characterize a simple scheme to minimize errors in entangling operations related to the residual excitation of mediating bosonic oscillator modes that both improves gate-robustness and provides scaling benefits in larger systems. The technique employs discrete phase shifts in the control field driving the gate operation, determined either analytically or numerically, to ensure all modes are de-excited at arbitrary user-defined times. We demonstrate an average gate fidelity of 99.4(2)% across a wide range of parameters in a system of 171 Yb + trapped ion qubits, and observe a reduction of gate error in the presence of common experimental error sources. Our approach provides a unified framework to achieve robustness against both static and time-varying laser amplitude and frequency detuning errors. We verify these capabilities through systemidentification experiments revealing improvements in error-susceptibility achieved in phase-modulated gates.The ability to perform robust, high fidelity entangling gates in multi-qubit systems is a key requirement for realizing scalable quantum information processing 1 . In several hardware architectures, qubits are entangled through shared bosonic oscillator modes via an interaction that is moderated by an external driving field. The Mølmer-Sørensen (MS) gate in trapped ions 2-4 and the resonator-induced phase gate in superconducting circuits 5-7 are both of this type. In addition, interactions simultaneously employing multiple bosonic modes have been explored to improve gate fidelities 8 and probe novel types of interactions 9 in superconducting circuits.A major source of error for oscillator-mediated gates is residual qubit-oscillator entanglement at the end of the operation 10 . This detrimental effect can arise due to the presence of quasi-static or time-varying noise on the driving field, slow drifts in experimental parameters such as the qubit and oscillator frequencies, or the presence of spectator modes that are not properly accounted for in the gate construction. In trapped ion systems, various schemes have been demonstrated that minimize this residual coupling 11-15 , with some also incorporating the ability to simultaneously decouple from multiple modes 16-21 . Their common feature is a temporal modulation of the driving field, modifying the trajectories of the joint qubit-oscillator states in each oscillator's phase space.In this work, we experimentally demonstrate a new class of phase-modulated (ΦM) entangling gates using trapped ions in the presence of multi-mode motional spectra. Specifically, we implement an MS-type interaca) These three authors contributed equally to this work. b) Current address: Fachrichtung Physik, Universität des Saarlandes, tion and employ discrete phase shifts of the driving field to suppress dominant gate errors. Using both an ana...

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“…Therefore, the conditions for attaining the equality in Eq. (18) and saturating the QCRB are |C 1,0 | = 1 [or W P (ω 0 ) = 0] and ω 0 T = 2Kπ. So all the schemes proposed in the examples (i) and (ii) with P (φ I ) measurements satisfy these conditions and thus saturate the QCRB.…”

Section: Precision and Sensitivitymentioning

confidence: 99%

“…However, open system effects, e.g., decoherence caused by inevitable noises, may reduce the fidelity of the Sagnac phase gate and therefore the expected sensing precision cannot be reached. On the other hand, geometric quantum gates have been studied theoretically [2][3][4][5][6][7][8][9][10][11] and demonstrated in experiments [12][13][14][15][16][17][18] for quantum computation. Compared to the dynamic phase, the geometric phase only depends on global geometric features (e.g., area, volume, genus, etc.)…”

Section: Introductionmentioning

confidence: 99%

Phase-space geometric Sagnac interferometer for rotation sensing

et al. 2018

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Quantum information processing with geometric features of quantum states may provide promising noiseresilient schemes for quantum metrology. In this work, we theoretically explore phase-space geometric Sagnac interferometers with trapped atomic clocks for rotation sensing, which could be intrinsically robust to certain decoherence noises and reach high precision. With the wave guide provided by sweeping ring-traps, we give criteria under which the well-known Sagnac phase is a pure or unconventional geometric phase with respect to the phase space. Furthermore, corresponding schemes for geometric Sagnac interferometers with designed sweeping angular velocity and interrogation time are presented, and the experimental feasibility is also discussed. Such geometric Sagnac interferometers are capable of saturating the ultimate precision limit given by the quantum Cramér-Rao bound.

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Continuous-variable geometric phase and its manipulation for quantum computation in a superconducting circuit

Cited by 90 publications

References 41 publications

Realisation of high-fidelity nonadiabatic CZ gates with superconducting qubits

Realisation of high-fidelity nonadiabatic CZ gates with superconducting qubits

Phase-Modulated Entangling Gates Robust to Static and Time-Varying Errors

Phase-space geometric Sagnac interferometer for rotation sensing

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