Abstract: Techniques for performing quantum information processing using an asymmetric error channel are provided. According to some aspects, a quantum information processing includes a data qubit and an ancilla qubit, the ancilla qubit having an asymmetric error channel. The data qubit is coupled to the ancilla qubit. The ancilla qubit may be driven with a stabilizing microwave field to create the asymmetric error channel.

Abstract: Systems and methods for performing fault tolerant quantum operations for the 4-legged cat code are provided. The quantum systems include an ancilla qubit dispersively coupled to a first logical qubit. and the quantum system may be operated at least in part by: generating and applying a first drive waveform to the ancilla qubit. the first drive waveform comprising a first comb of 7t-pulses having selective frequencies corresponding to a first selection of even and odd cavity resonance frequencies of the first logical qubit: and reading out a state of the ancilla qubit.

Abstract: Quantum systems and techniques are described to generate fault tolerant cluster states for use in quantum computation, quantum networking, and other applications. The systems and techniques include initializing states in first qubits and generating initial resource states by performing first Pauli product measurements on sets of X-type and/or Z-type qubits of the first qubits, the initial resource states comprising qubit cluster states comprising at least three qubits. The final cluster state may then be generated by fusing two or more initial resource states, the fusing comprising performing second Pauli product measurements between qubits of two or more of the initial resource states.

Abstract: Parametrically pumped four-wave mixing is a key building block for many developments in the field of superconducting quantum information processing. However, undesired frequency shifts such as Kerr, cross-Ken and Stark shifts inherent with four-wave mixing, lead to difficulties in tuning up the desired parametric processes and, for certain applications, severely limit the fidelities of the resulting operations. Some embodiments include a Josephson four-wave mixing device consisting of a SQUID transmon coupled to a half-flux biased SNAIL transmon, a.k.a. capacitively shunted flux qubit. When the two transmon have matching frequencies, an interference effect cancels the negative Kerr of the SQUID transmon with the positive Kerr of the SNAIL transmon while preserving parametric four-wave mixing capabilities.

Abstract: Parametrically pumped four-wave mixing is a key building block for many developments in the field of superconducting quantum information processing. However, undesired frequency shifts such as Kerr, cross-Ken and Stark shifts inherent with four-wave mixing, lead to difficulties in tuning up the desired parametric processes and, for certain applications, severely limit the fidelities of the resulting operations. Some embodiments include a Josephson four-wave mixing device consisting of a SQUID transmon coupled to a half-flux biased SNAIL transmon, a.k.a. capacitively shunted flux qubit. When the two transmon have matching frequencies, an interference effect cancels the negative Kerr of the SQUID transmon with the positive Kerr of the SNAIL transmon while preserving parametric four-wave mixing capabilities.

Abstract: Techniques for performing quantum information processing using an asymmetric error channel are provided. According to some aspects, a quantum information processing includes a data qubit and an ancilla qubit, the ancilla qubit having an asymmetric error channel. The data qubit is coupled to the ancilla qubit. The ancilla qubit may be driven with a stabilizing microwave field to create the asymmetric error channel.

Abstract: Techniques for performing quantum information processing using an asymmetric error channel are provided. According to some aspects, a quantum information processing includes a data qubit and an ancilla qubit, the ancilla qubit having an asymmetric error channel. The data qubit is coupled to the ancilla qubit. The ancilla qubit may be driven with a stabilizing microwave field to create the asymmetric error channel.

Abstract: A method of quantum processing using a quantum processor comprising a plurality of Kerr non-linear oscillators (KNOs), each operably drivable by both i) a controllable single-boson drive and ii) a controllable two-boson drive, the method comprising simultaneously controlling a drive frequency and a drive amplitude of the controllable single-boson drives to define a problem and controlling a drive frequency and a drive amplitude of the two-photon drives to define the Hilbert space, including increasing the amplitude of the two-boson drive and reaching both amplitude conditions a) 4 times the amplitude of the two-boson drives being greater than the loss rate, and b) the amplitude of the two-boson drives being greater than the amplitude of the single-boson drive, and maintaining both amplitude conditions a) and b) until a solution to the problem is reached; and reading the solution.

Abstract: A method of quantum processing using a quantum processor comprising a plurality of Kerr non-linear oscillators (KNOs), each operably drivable by both i) a controllable single-boson drive and ii) a controllable two-boson drive, the method comprising simultaneously controlling a drive frequency and a drive amplitude of the controllable single-boson drives to define a problem and controlling a drive frequency and a drive amplitude of the two-photon drives to define the Hilbert space, including increasing the amplitude of the two-boson drive and reaching both amplitude conditions a) 4 times the amplitude of the two-boson drives being greater than the loss rate, and b) the amplitude of the two-boson drives being greater than the amplitude of the single-boson drive, and maintaining both amplitude conditions a) and b) until a solution to the problem is reached; and reading the solution.