Single flux quantum source for projective measurements
AssigneeD-Wave Systems Inc.
InventorsEmile M. Hoskinson, Reuble Mathew
Life of this patent
Estimating the term…
Abstract
Devices, systems, and methods that include a qubit coupled to a projective-source digital-to-analog converter (PSDAC) for projective measurement of the qubit. A change in flux state of the PSDAC from a first flux state to a second flux state generates a fast-flux step or fast-step waveform that can be applied to the qubit to perform projective measurement of the qubit. For a quantum processor that includes a set of qubits wherein each qubit is coupled to a respective PSDAC, a shared trigger line can activate each PSDAC to generate a respective fast-flux step or fast-step waveform. Synchronization devices can synchronize the fast-flux steps or fast-step waveforms, allowing for projective readout of the set of qubits.
Claims20
A system for projective measurement of qubits in a quantum processor, the system comprising:
- a plurality of qubits, each qubit having a body loop and a Josephson Junction (JJ) loop;
- a plurality of projective-source digital-to-analog converters (PSDACs), each PSDAC having a body loop and a JJ loop, wherein each body loop of each PSDAC is communicatively coupled to the JJ loop of a respective qubit of the plurality of qubits;
- a trigger line communicatively coupled to the JJ loop of each PSDAC of the plurality of PSDACs, the trigger line operable to activate each PSDAC to change from a first flux state to a second flux state, wherein activating each PSDAC to change from a first flux state to a second flux state generates a respective fast flux step;
- and
- a plurality of synchronization devices, each synchronization device communicatively coupled to the JJ loop of a respective PSDAC of the plurality of PSDACs, wherein each synchronization device is operable to apply a bias to the JJ loop of the respective PSDAC.
A method of operation of a system for projective measurement of a qubit in a quantum processor, the system including:
- a plurality of qubits, each qubit having a body loop and a Josephson Junction (JJ) loop;
- a plurality of projective-source digital-to-analog converters (PSDACs), each PSDAC having a body loop and a JJ loop, wherein each body loop of each PSDAC is communicatively coupled to the JJ loop of a respective qubit of the plurality of qubits;
- a trigger line communicatively coupled to the JJ loop of each PSDAC of the plurality of PSDACs, the trigger line operable to activate each PSDAC to change from a first flux state to a second flux state, wherein activating each PSDAC to change from a first flux state to a second flux state generates a respective fast flux step;
- and
- a plurality of synchronization devices, each synchronization device communicatively coupled to the JJ loop of a respective PSDAC of the plurality of PSDACs, wherein each synchronization device applies a bias to the JJ loop of the respective PSDAC, the method comprising:
- initiating a quantum annealing evolution performed by the quantum processor;
- at a point during the quantum evolution:
- sending a signal through the trigger line to activate a PSDAC of the plurality of PSDACs;
- changing a flux state of the PSDAC of the plurality of PSDACs from a first flux state to a second flux state to generate a fast flux step;
- raising an energy barrier of a qubit of the plurality of qubits using the fast flux step;
- and
- measuring a spin state of the qubit of the plurality of qubits.
Dependencies are inferred from the claim text.