Frequency Fluctuations in Tunable and Nonlinear Microwave Cavities

Brock, B. L.; Blencowe, M. P.; Rimberg, A. J.

doi:10.1103/physrevapplied.14.054026

Cited by 10 publications

(3 citation statements)

References 71 publications

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“…The cCPT sample used for the following measurements exhibits a total tunability of about 140 MHz, centered about the bare cavity frequency at 5.757 GHz. Following a model that accounts for frequency fluctuations in the cavity [42], the typical external and internal damping rates observed at (n g , Φ ext ) = (0, 0) are ∼0.97 MHz and ∼0.3 MHz, respectively. We therefore fix the modulation frequency ω m to be 30 MHz, one order of magnitude higher than the total damping rate.…”

Section: A Circuitrymentioning

confidence: 99%

“…Notice that r n (t) takes the general form of a reflectioncoefficient at ω c + nω m , but is slowly time-varying due to the low-frequency fluctuations in cavity resonance itself. Typical measurements of cavity reflection coefficients using a vector network analyzer outputs the value averaged over the measurement time, and often smears out the effects of these resonant fluctuations [42,43].…”

Section: Introductionmentioning

confidence: 99%

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Feedback stabilization of the resonant frequency in tunable microwave cavities with single-photon occupancy

Kanhirathingal¹,

Thyagarajan²,

Brock³

et al. 2022

Preprint

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We successfully demonstrate low-frequency noise suppression in the resonant frequency fluctuations of a cavity-embedded Cooper pair transistor (cCPT) driven at single-photon occupancy. In particular, we report a reduction in the resonant frequency fluctuations caused by the internal charge noise over a bandwidth of ∼1.4 kHz when the cavity is driven at an average photon number n = 10, and a bandwidth of 11 Hz for average n = 1. The gate-dependent tunability of the cCPT allows us to implement a feedback-scheme, derived from the Pound-Drever-Hall locking technique. This reduces fluctuations due to intrinsic charge-noise, which otherwise interferes with the cCPT's operation as a near quantum-limited electrometer. We believe our technique can be generalized to achieve frequency stabilization in tunable microwave resonators that play a vital role in today's quantum computing architecture, thereby moderating the limitations in detection caused by the intrinsic 1/f -noise on such circuit devices. The work discusses the various aspects relating to the operation of a fully functional feedback loop down to the single-photon level.

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Section: A Circuitrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Feedback stabilization of the resonant frequency in tunable microwave cavities with single-photon occupancy

Kanhirathingal¹,

Thyagarajan²,

Brock³

et al. 2022

Preprint

Self Cite

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“…We attribute this discrepancy to two factors. First and foremost, the resonant frequency fluctuates due to 1/f charge and flux noise [30,38] over the course of each measurement, which means our carrier is not always on resonance. On average, this reduces the output sideband power yielding worse charge sensitivity than expected.…”

mentioning

confidence: 99%

Fast and Ultrasensitive Electrometer Operating at the Single-Photon Level

Brock,

Li,

Kanhirathingal

et al. 2021

Preprint

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We demonstrate fast and ultrasensitive charge detection with a cavity-embedded Cooper pair transistor via dispersive readout of its Josephson inductance. We report a minimum charge sensitivity of 14 µe/ √ Hz with a detection bandwidth on the order of 1 MHz using 16 attowatts of power, corresponding to the single-photon level of the cavity. In addition, our measured sensitivities are within a factor of 5 of the quantum limit for this device. This is the first ultrasensitive electrometer reported to operate at the single-photon level and its sensitivity is comparable to rf-SETs, which typically require picowatts of power. Our results support the feasibility of using this device to mediate an optomechanical interaction that reaches the single-photon strong coupling regime.

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Four-wave-cooling to the single phonon level in Kerr optomechanics

2022

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Cavity optomechanics has achieved groundbreaking control and detection of mechanical oscillators, based on their coupling to linear electromagnetic modes. Recently, however, there is increasing interest in cavity nonlinearities as resource in radiation-pressure interacting systems. Here, we present a flux-mediated optomechanical device combining a nonlinear superconducting quantum interference cavity with a mechanical nanobeam. We demonstrate how the Kerr nonlinearity of the circuit can be used to enhance the device performance by suppressing cavity frequency noise, and for a counter-intuitive sideband-cooling scheme based on intracavity four-wave-mixing. With a large single-photon coupling rate of up to g0 = 2π ⋅ 3.6 kHz and a high mechanical quality factor Qm ≈ 4 ⋅ 105, we achieve an effective four-wave cooperativity of $${{{{{{{{\mathcal{C}}}}}}}}}_{{{{{{{{\rm{fw}}}}}}}}}\, > \, 100$$ C fw > 100 and demonstrate four-wave cooling of the mechanical oscillator close to its quantum groundstate. Our results advance the recently developed platform of flux-mediated optomechanics and demonstrate how cavity Kerr nonlinearities can be utilized in cavity optomechanics.

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Frequency Fluctuations in Tunable and Nonlinear Microwave Cavities

Cited by 10 publications

References 71 publications

Feedback stabilization of the resonant frequency in tunable microwave cavities with single-photon occupancy

Feedback stabilization of the resonant frequency in tunable microwave cavities with single-photon occupancy

Fast and Ultrasensitive Electrometer Operating at the Single-Photon Level

Four-wave-cooling to the single phonon level in Kerr optomechanics

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