Device-tailored model-free error correction in quantum processors

A system comprising:

• a quantum circuit, comprising an encoding circuit and a decoding circuit, the quantum circuit configured to:
• apply the encoding circuit to each of a plurality of training states and to a plurality of input syndrome qubits, each training state comprising a plurality of logical qubits, and each syndrome qubit having a default state, to produce encoded training states;
• apply the decoding circuit to the encoded training states to determine a plurality of outputs;
• measure a fidelity of the quantum circuit for the plurality of training states based on the plurality of outputs;
• providing the fidelity to a computing node, and
• a computing node comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor of the computing node to cause the processor to perform a method comprising:
• configuring the quantum circuit according to a plurality of configuration parameters;
• inputting each of a plurality of training states to the quantum circuit;
• receiving the fidelity from the quantum circuit;
• determining a first plurality of optimized configuration parameters, the optimized configuration parameters maximizing the accuracy of the encoding circuit for the plurality of training states.

A computer program product for error correction in a quantum circuit, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause the processor to perform a method comprising:

• configuring a quantum circuit according to a plurality of configuration parameters, the quantum circuit comprising an encoding circuit and a decoding circuit;
• inputting each of a plurality of training states to the quantum circuit, each training state comprising a plurality of logical qubits;
• receiving a fidelity of the quantum circuit for the plurality of training states from the quantum circuit, the fidelity being determined by the quantum circuit by applying the encoding circuit to each of the plurality of training states and to a plurality of input syndrome qubits, each syndrome qubit having a ground state, to produce encoded training states and applying the decoding circuit to the encoded training states to determine a plurality of outputs;
• determining a first plurality of optimized configuration parameters, the first plurality of optimized configuration parameters maximizing the accuracy of the quantum circuit for the plurality of training states.

A method for configuring a quantum memory, the method comprising:

• selecting a quantum circuit from a plurality of quantum circuits, the plurality of quantum circuits being arranged in series;
• configuring the quantum circuit according to a plurality of configuration parameters, the quantum circuit comprising an encoding circuit and a decoding circuit;
• inputting each of a plurality of training states to the quantum circuit, each training state comprising a plurality of logical qubits;
• applying the encoding circuit to each of the plurality of training states and to a plurality of input syndrome qubits, each syndrome qubit having a default state, to produce encoded training states;
• applying the decoding circuit to the encoded training states to determine a plurality of outputs;
• measuring a fidelity of the quantum circuit for the plurality of training states based on the plurality of outputs;
• providing the fidelity to a computing node;
• determining a first plurality of optimized configuration parameters by the computing node, the first plurality of optimized configuration parameters maximizing the accuracy of the quantum circuit for the plurality of training states.

A quantum memory comprising:

• a plurality of quantum circuits arranged in series, each quantum circuit comprising an encoding circuit and a decoding circuit, each quantum circuit being configured to:
• apply the encoding circuit to each of a plurality of training states and to a plurality of input syndrome qubits, each training state comprising a plurality of logical qubits, and each syndrome qubit having a default state, to produce encoded training states;
• apply the decoding circuit to the encoded training states to determine a plurality of outputs;
• measure a fidelity of the quantum circuit for the plurality of training states based on the plurality of outputs;
• providing the fidelity to a computing node;
• a computing node comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor of the computing node to cause the processor to perform a method comprising:
• configuring each quantum circuit according to a plurality of configuration parameters;
• inputting each of a plurality of training states to each quantum circuit;
• receive the fidelity from each quantum circuit;
• determine a first plurality of optimized configuration parameters, the first plurality of optimized configuration parameters maximizing the fidelity of each quantum circuit for the plurality of training states.

A method for error correction in a quantum circuit, the method comprising:

• configuring a quantum circuit according to a plurality of configuration parameters, the quantum circuit comprising an encoding circuit and a decoding circuit;
• providing each of a plurality of training states to the quantum circuit, each training state represented by a plurality of logical qubits;
• applying the encoding circuit to the logical qubits representing each of the plurality of training states and to a plurality of input syndrome qubits having a default state, to produce encoded training states;
• applying a logic circuit to the encoded training states and to a plurality of refresh qubits having a default state to determine a plurality of encoded outputs;
• applying the decoding circuit to each of the plurality of encoded outputs to determine a plurality of unencoded outputs;
• applying an inverse of the logic circuit to the plurality of unencoded outputs to determine a plurality of circuit outputs;
• measuring a fidelity of the quantum circuit for the plurality of training states based on the plurality of circuit outputs;
• providing the fidelity to a computing node;
• determining a plurality of optimized configuration parameters by the computing node, the plurality of optimized configuration parameters maximizing the fidelity of the logic circuit for the plurality of training states.

A method for error correction in a quantum circuit, the method comprising:

• configuring a quantum circuit according to a plurality of configuration parameters, the quantum circuit comprising an encoding circuit, a sensing circuit, and a decoding circuit;
• providing a control signal to the quantum circuit, the control signal represented by a plurality of qubits;
• applying the encoding circuit to the qubits representing the control signal and to a plurality of input syndrome qubits having a default state, to produce an encoded control state;
• exposing the sensing circuit to a plurality of training conditions to determine a plurality of noisy sensor signals;
• applying the decoding circuit to the plurality of noisy sensor signals to determine a plurality of outputs;
• measuring a fidelity of the quantum circuit for the plurality of training conditions based on the plurality of outputs;
• providing the fidelity to a computing node;
• determining a plurality of optimized configuration parameters by the computing node, the plurality of optimized configuration parameters maximizing the fidelity of the quantum circuit for the plurality of training conditions.

A method for error correction in quantum communication, the method comprising:

• configuring a quantum circuit according to a plurality of configuration parameters, the quantum circuit comprising an encoding circuit;
• providing each of a plurality of training states to the quantum circuit, each training state represented by a plurality of logical qubits;
• applying the encoding circuit to the logical qubits representing each of the plurality of training states and to a plurality of input syndrome qubits having a default state, to produce encoded training states;
• transmitting the encoded training states via a communications channel to a receiver;
• measuring a fidelity of the quantum circuit for the plurality of training states based on the encoded training states as received by the receiver;
• providing the fidelity to a computing node;
• determining a plurality of optimized configuration parameters by the computing node, the plurality of optimized configuration parameters maximizing the fidelity of the encoding circuit for the plurality of training states and the communications channel.