Resonator tuning
AssigneeMicrosoft Technology Licensing, LLC
InventorsTareq El DANDACHI, Thorvald Wadum LARSEN, Benjamin James CHAPMAN
Life of this patent
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Abstract
A method for exciting a resonator at an estimated resonance frequency of the resonator comprises: (a) varying a frequency of an input signal applied to the resonator while recording an output signal from the resonator; (b) for each of a series of frequency values of the input signal, computing noise-filtered, complex first and second derivatives of a ratio of the output signal to the input signal; (c) for each of the series of frequency values of the input signal, computing a real part of a dot product of the complex first and second derivatives as vectors projected onto a complex plane; and (d) exciting the resonator an excitation frequency where the real part vanishes.
Claims20
A method for exciting a resonator at an estimated resonance frequency of the resonator, the method comprising:
- varying a frequency of an input signal applied to the resonator while recording an output signal from the resonator;
- for each of a series of frequency values of the input signal, computing noise-filtered, complex first and second derivatives of a ratio of the output signal to the input signal;
- for each of the series of frequency values of the input signal, computing a real part of a dot product of the complex first and second derivatives as vectors projected onto a complex plane;
- and
- exciting the resonator an excitation frequency where the real part of the dot product vanishes.
A quantum computer comprising:
- a physical qubit;
- a resonator coupled to the physical qubit;
- a readout chain coupled to the resonator;
- a signal generator coupled to the readout chain and configured to excite the readout chain with a signal of an estimated resonance frequency, the estimated resonance frequency found by:
- varying a frequency of an input signal applied to the resonator while recording an output signal from the resonator,
- for each of a series of frequency values of the input signal, computing noise-filtered, complex first and second derivatives of a ratio of the output signal to the input signal,
- for each of the series of frequency values of the input signal, computing a real part of a dot product of the complex first and second derivatives as vectors projected onto a complex plane, and
- returning as the estimated resonance frequency a frequency where the real part of the dot product vanishes.
A method for exciting a resonator at an estimated resonance frequency of the resonator, the method comprising:
- varying a frequency of an input signal applied to the resonator while recording an output signal from the resonator;
- for each of a series of frequency values of the input signal, computing noise-filtered, complex first and second derivatives of a ratio of the output signal to the input signal;
- for each of the series of frequency values of the input signal, computing a real part of a dot product of the complex first and second derivatives as vectors projected onto a complex plane;
- extracting a resonator-quality metric from an imaginary part of the dot product evaluated at the frequency where the real part vanishes;
- and
- exciting the resonator a frequency where the real part of the dot product vanishes.
Dependencies are inferred from the claim text.