Single flux quantum source for projective measurements
Assignee1372934 B.C. Ltd.
InventorsEmile M. Hoskinson, Reuble Mathew
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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;
- one or more trigger lines, each of the one or more trigger lines respectively communicatively coupled to the JJ loop of one or more of the plurality of PSDACs such that each JJ loop is communicatively coupled to one of the one or more trigger lines, the one or more trigger lines operable to provide signals 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 flux bias sources, each synchronization flux bias source communicatively coupled to the JJ loop of a respective PSDAC of the plurality of PSDACs, wherein each synchronization flux bias source is operable to apply a flux 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;
- one or more trigger lines, each of the one or more trigger lines respectively communicatively coupled to the JJ loop of one or more of the plurality of PSDACs such that each JJ loop is communicatively coupled to one of the one or more trigger lines, the one or more trigger lines operable to provide signals 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 flux bias sources, each synchronization flux bias source communicatively coupled to the JJ loop of a respective PSDAC of the plurality of PSDACs, wherein each synchronization flux bias source 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 a first trigger line of the one or more trigger lines 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 first 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.