标题： 具有振荡电压偏置的超导电路中的自校正GKP量子比特 显示英文标题

标题： Self-correcting GKP qubit in a superconducting circuit with an oscillating voltage bias

摘要： 我们提出一种用于耗散错误校正的Gottesman-Kitaev-Preskill（GKP）量子比特的简单电路架构。该装置包括一个阻抗为$h/2e^2\approx 12.91\,{\rm k}\Omega$的电磁谐振器，与一个在谐振器频率两倍处振荡的电压偏置约瑟夫森结相连。对于大驱动振幅，该电路可由GKP稳定子哈密顿量有效描述，其低能子空间构成对相空间局部噪声具有保护作用的量子比特码空间。码空间中的GKP态可通过通过带通滤波器将谐振器耦合到浴体来耗散地稳定和错误校正；产生的边带冷却效应可使系统稳定在GKP码空间中，耗散地校正比特翻转和相位翻转错误。仿真显示，使用基于NbN的结，在操作温度处于$\sim 100\,{\rm mK}$范围时，这种耗散错误校正可将相干时间提高$\sim 1000$倍。该方案可用于稳定方形和六边形晶格GKP码。最后，提出了基于约瑟夫森电流的读出方案以及耗散校正的单量子比特Clifford门。 显示英文摘要

摘要： We propose a simple circuit architecture for a dissipatively error corrected Gottesman-Kitaev-Preskill (GKP) qubit. The device consists of a electromagnetic resonator with impedance $h/2e^2\approx 12.91\,{\rm k}\Omega$ connected to a Josephson junction with a voltage bias oscillating at twice the resonator frequency. For large drive amplitudes, the circuit is effectively described by the GKP stabilizer Hamiltonian, whose low-energy subspace forms the code space for a qubit protected against phase-space local noise. The GKP states in the codespace can be dissipatively stabilized and error corrected by coupling the resonator to a bath through a bandpass filter; a resulting side-band cooling effect stabilizes the system in the GKP code space, dissipatively correcting it against both bit and phase flip errors. Simulations show that this dissipative error correction can enhance coherence time by factor $\sim 1000$ with NbN-based junctions, for operating temperatures in the $\sim 100\,{\rm mK}$ range. The scheme can be used to stabilize both square- and hexagonal-lattice GKP codes. Finally, a Josephson current based readout scheme, and dissipatively corrected single-qubit Clifford gates are proposed.