A system for transmission of quantum information for quantum error correction includes an ancilla qubit chip including a plurality of ancilla qubits, and a data qubit chip spaced apart from the ancilla qubit chip, the data qubit chip including a plurality of data qubits. The system includes an interposer coupled to the ancilla qubit chip and the data qubit chip, the interposer including a dielectric material and a plurality of superconducting structures formed in the dielectric material. The superconducting structures enable transmission of quantum information between the plurality of data qubits on the data qubit chip and the plurality of ancilla qubits on the ancilla qubit chip via virtual photons for quantum error correction.

A system for transmission of quantum information for quantum error correction includes an ancilla qubit chip including a plurality of ancilla qubits, and a data qubit chip spaced apart from the ancilla qubit chip, the data qubit chip including a plurality of data qubits. The system includes an interposer coupled to the ancilla qubit chip and the data qubit chip, the interposer including a dielectric material and a plurality of superconducting structures formed in the dielectric material. The superconducting structures enable transmission of quantum information between the plurality of data qubits on the data qubit chip and the plurality of ancilla qubits on the ancilla qubit chip via virtual photons for quantum error correction.

A feedback controller is provided to generate a quantum feedback operation to control one or more ancilla qubits in a quantum error correcting code. The quantum feedback operation is based on the measurement of the one or more ancilla qubits. The feedback controller is operable to dynamically adjust a state discrimination according to previous measurements of the one or more ancilla qubits.

A feedback controller is provided to generate a quantum feedback operation to control one or more ancilla qubits in a quantum error correcting code. The quantum feedback operation is based on the measurement of the one or more ancilla qubits. The feedback controller is operable to dynamically adjust a state discrimination according to previous measurements of the one or more ancilla qubits.

Orthogonal neural networks impose orthogonality on the weight matrices. They may achieve higher accuracy and avoid evanescent or explosive gradients for deep architectures. Several classical gradient descent methods have been proposed to preserve orthogonality while updating the weight matrices, but these techniques suffer from long running times and provide only approximate orthogonality. In this disclosure, we introduce a new type of neural network layer. The layer allows for gradient descent with perfect orthogonality with the same asymptotic running time as a standard layer. The layer is inspired by quantum computing and can therefore be applied on a classical computing system as well as on a quantum computing system. It may be used as a building block for quantum neural networks and fast orthogonal neural networks.

Orthogonal neural networks impose orthogonality on the weight matrices. They may achieve higher accuracy and avoid evanescent or explosive gradients for deep architectures. Several classical gradient descent methods have been proposed to preserve orthogonality while updating the weight matrices, but these techniques suffer from long running times and provide only approximate orthogonality. In this disclosure, we introduce a new type of neural network layer. The layer allows for gradient descent with perfect orthogonality with the same asymptotic running time as a standard layer. The layer is inspired by quantum computing and can therefore be applied on a classical computing system as well as on a quantum computing system. It may be used as a building block for quantum neural networks and fast orthogonal neural networks.

Systems, computer-implemented methods, and computer program products to facilitate generation of a visualization scheme of noise in a quantum circuit are provided. According to an embodiment, a system can comprise a processor that executes computer executable components stored in memory. The computer executable components can comprise a calculation component that can calculate a noise state of a layer in a quantum circuit. The computer executable components can further comprise a visualization component that can render a visual representation of the noise state at the layer in the quantum circuit.

Methods, systems and apparatus for estimating quantum processor performance. In one aspect, a method includes defining a benchmarking circuit configured to operate on an array of qubits, wherein the benchmarking circuit comprises one or more cycles of quantum gates, each cycle comprising a respective layer of randomly sampled single-qubit gates and a layer of multiple instances of a same multi-qubit gate; partitioning the defined benchmarking circuit into two or more sub-circuits, comprising: defining one or more boundaries between qubits in the array of qubits, removing instances of the multi-qubit gate that cross the defined one or more boundaries to create the two or more sub-circuits; performing a benchmarking process using the partitioned benchmarking circuit to estimate a respective circuit fidelity of each of the sub-circuits; and multiplying the estimated circuit fidelities of each of the sub-circuits to obtain an estimate of the fidelity of the quantum processor.

Methods, systems and apparatus for estimating quantum processor performance. In one aspect, a method includes defining a benchmarking circuit configured to operate on an array of qubits, wherein the benchmarking circuit comprises one or more cycles of quantum gates, each cycle comprising a respective layer of randomly sampled single-qubit gates and a layer of multiple instances of a same multi-qubit gate; partitioning the defined benchmarking circuit into two or more sub-circuits, comprising: defining one or more boundaries between qubits in the array of qubits, removing instances of the multi-qubit gate that cross the defined one or more boundaries to create the two or more sub-circuits; performing a benchmarking process using the partitioned benchmarking circuit to estimate a respective circuit fidelity of each of the sub-circuits; and multiplying the estimated circuit fidelities of each of the sub-circuits to obtain an estimate of the fidelity of the quantum processor.

A method includes receiving a plurality of quantum systems, wherein each quantum system of the plurality of quantum system includes a plurality of quantum sub-systems in an entangled state, and wherein respective quantum systems of the plurality of quantum systems are independent quantum systems that are not entangled with one another. The method further includes performing a plurality of joint measurements on different quantum sub-systems from respective ones of the plurality of quantum systems, wherein the joint measurements generate joint measurement outcome data and determining, by a decoder, a plurality of syndrome graph values based on the joint measurement outcome data.