Characterization of time-correlated quantum errors through entanglement

A system for operating a quantum computer, the system comprising:

• one or more processors;
• one or more I/O devices coupled to the one or more processors and configured to send control signals to and receive readout signals from the quantum computer;
• and
• one or more memories having stored thereon computer readable instructions configured to cause the one more processors and the one or more I/O devices to carry out operations on the quantum computer, the operations comprising:
• repeatedly performing a plurality of operations, the plurality of operations comprising
• initializing N qubits of the quantum computer in a highly entangled state that allows the amplification of quantum errors through coherent phase accumulation,
• accumulating quantum errors in the highly entangled state, and
• measuring the accumulated errors;
• and
• obtaining an ensemble average of the accumulated errors from repeated performing of the plurality of operations;
• wherein the repeated performing of the plurality of operations is completed on a measurement time scale less than a characteristic time scale for drift of quantum errors in the quantum computer.

A non-transitory computer readable medium storing instructions for execution by one more or more computers configured to send control signals to and receive readout signals from a quantum computer, the instructions causing the one or more computers to carry out operations on the quantum computer, the operations comprising:

• repeatedly performing a plurality of operations, the plurality of operations comprising
• initializing N qubits of the quantum computer in a highly entangled state that allows the amplification of quantum errors through coherent phase accumulation,
• accumulating quantum errors in the highly entangled state, and
• measuring the accumulated errors;
• and
• obtaining an ensemble average of the accumulated errors from repeated performing of the plurality of operations;
• wherein the repeated performing of the plurality of operations is completed on a measurement time scale less than a characteristic time scale for drift of quantum errors in the quantum computer.