Abstract: Systems and methods for estimating a property of an error in a circuit implemented on an n-qubit quantum system are provided, where the circuit comprises a gate set that comprises a first subset () and a second subset () of elementary gates. The first subset comprises a third subset () of elementary gates each of which consists of an n-fold tensor product of a plurality of single qubit gates. A first procedure is executed that comprises preparing the system in a state ? and then applying D1=T1 to the system. The procedure further comprises, for each respective clock cycle t in clock cycles t?{2, . . . , m+1}, (a) applying H to the system, where H is an elementary gate in the second subset, and then (b) applying a gate Dt=TtGHTt?1†H† to the system, where Dt is an element of the first subset. The procedure further comprises performing a measurement readout R.

Abstract: Systems and methods for estimating crosstalk in a quantum system are provided. The quantum system comprises a plurality of qudits. A plurality of interacting systems within the plurality of qudits during a quantum operation are identified. Each such interacting system comprises a subset of the plurality of qudits. A set of components is identified from the plurality of interacting systems. Each given component in the set of components is evolved along with the respective components in the set of components that interact with the given component in the quantum operation, thereby forming a plurality of maps for the set of components. For each respective component in the set of components, a corresponding marginal distribution is calculated using the corresponding map for the respective component, thereby computing a plurality of marginal distributions. An estimate of the Pauli error distribution is constructed for the quantum operation from the plurality of marginal distributions.

Abstract: Computer systems and methods for estimating errors for a quantum system comprising a set of n qubits are provided in which is the projective n-qubit Pauli group for the quantum system, and n is a fixed integer of three or greater. At least a first and second subset of Pauli matrices are identified. The Pauli fidelities f1 of the first subset of Pauli fidelities are estimated. The fixed probability distribution ?2 for the second subset of Pauli matrices are reconstructed using the Pauli fidelities f1 of the first subset of Pauli matrices, thereby estimating errors for the quantum system.

Abstract: In a general aspect, randomized compiling techniques for quantum computing are described. In some aspects, an initial quantum-logic gate sequence is received. A modified quantum-logic gate sequence is generated by applying virtual random gates to the initial quantum-logic gate sequence, such that the initial quantum-logic gate sequence is logically equivalent to the modified quantum-logic gate sequence. The modified quantum-logic gate sequence can be provided to a quantum information processor for execution.

Abstract: Systems and methods for estimating a property of an error in a circuit implemented on an n-qubit quantum system are provided, where the circuit comprises a gate set that comprises a first subset () and a second subset () of elementary gates. The first subset comprises a third subset () of elementary gates each of which consists of an n-fold tensor product of a plurality of single qubit gates. A first procedure is executed that comprises preparing the system in a state ? and then applying D1=T1 to the system. The procedure further comprises, for each respective clock cycle t in clock cycles t?{2, . . . , m+1}, (a) applying H to the system, where H is an elementary gate in the second subset, and then (b) applying a gate Dt=TtGHTt?1†H† to the system, where Dt is an element of the first subset. The procedure further comprises performing a measurement readout R.

Abstract: Systems and methods for executing a quantum computation comprising a plurality gates on a quantum information processor are provided. An initial quantum-logic gate sequence comprising the plurality of gates is received. Then, for each instance in a plurality of instances, a procedure is performed. In each instance of the procedure a respective modified quantum-logic gate sequence is generated by applying a virtual random gate to a first single-qubit gate in the plurality of gates. The respective modified quantum-logic gate sequence is then executed on the quantum device to obtain a respective outcome. The respective outcome across the plurality of instances of the procedure is averaged to obtain a noise-tailored outcome for the initial quantum-logic gate sequence.

Abstract: Systems and methods for executing a quantum computation comprising a plurality gates on a quantum information processor are provided. An initial quantum-logic gate sequence comprising the plurality of gates is received. Then, for each instance in a plurality of instances, a procedure is performed. In each instance of the procedure a respective modified quantum-logic gate sequence is generated by applying a virtual random gate to a first single-qubit gate in the plurality of gates. The respective modified quantum-logic gate sequence is then executed on the quantum device to obtain a respective outcome. The respective outcome across the plurality of instances of the procedure is averaged to obtain a noise-tailored outcome for the initial quantum-logic gate sequence.

Abstract: In a general aspect, randomized compiling techniques for quantum computing are described. In some aspects, an initial quantum-logic gate sequence is received. A modified quantum-logic gate sequence is generated by applying virtual random gates to the initial quantum-logic gate sequence, such that the initial quantum-logic gate sequence is logically equivalent to the modified quantum-logic gate sequence. The modified quantum-logic gate sequence can be provided to a quantum information processor for execution.