Fast and high-fidelity quantum logic gates with superconducting circuits

Jerry M. Chow, Antonio D. Corcoles, Jay Gambetta +10 more

Muhammet Ali Yurtalan, Jiahao Shi, Graydon J. K. Flatt +1 more

We present the design and characterization of a three-Josephson-junction superconducting loop circuit with three large shunt capacitors. Used as a qubit, the circuit shows long energy-relaxation times, of the order of $40\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{s}$ and a spin-echo dephasing time of $9.4\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{s}$. The circuit has high anharmonicity, of $2\ensuremath{\pi}\ifmmode\times\else\texttimes\fi{}3.69\phantom{\rule{0.2em}{0ex}}\mathrm{GHz}$. We extract the multilevel relaxation and dephasing rates of the circuit used as a qutrit and discuss the possible sources for the decoherence. The high anharmonicity allows for fast qubit control with nanosecond-range gate durations and a measured average gate fidelity of 99.92%, characterized by randomized benchmarking. These results demonstrate interesting potential use for fast nanosecond-time-scale two-qubit gates and multilevel quantum logic.

Zheng‐Yuan Xue, Jian Zhou, Yaoming Chu +1 more

The implementation of holonomic quantum computation on superconducting quantum circuits is challenging due to the general requirement of controllable complicated coupling between multilevel systems. Here we solve this problem by proposing a scalable circuit QED lattice with simple realization of a universal set of nonadiabatic holonomic quantum gates. Compared with the existing proposals, we can achieve both the single and two logical qubit gates in a tunable and all-resonant way through a hybrid transmon--transmission-line encoding of the logical qubits in the decoherence-free subspaces. This distinct advantage thus leads to quantum gates with very fast speeds and consequently very high fidelities. Therefore, our scheme paves a promising way towards the practical realization of high-fidelity nonadiabatic holonomic quantum computation.

Matthias Steffen, R. McDermott, Ken B. Cooper +7 more

Zheng‐Yuan Xue, Jian Zhou, Yong Hu

The implementation of holonomic quantum computation in superconducting quantum circuits is challenging due to the general requirement of controllable complicated coupling between multi-level systems. In this Letter, we solve this problem by proposing a scalable circuit QED lattice with simple realization of the universal set of non-adiabatic holonomic quantum computation. Compared with existed proposals, here we can achieve both the single- and two- logical qubit gates in an unprecedented tunable and all-resonant way through a hybrid transmon-transmission-line encoding of the logical qubits in the decoherence-free subspaces. This distinct advantage thus leads to quantum gates with very fast speeds and consequently very high fidelities. Our scheme therefore paves a promising way towards the realization of high fidelity universal holonomic quantum computation.

Leszek Jaroszynski