Transmon-qubit readout using in-situ bifurcation amplification in the mesoscopic regime

Fuente: arXiv
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Main Authors: Dassonneville, R., Ramos, T., Milchakov, V., Mori, C., Planat, L., Foroughi, F., Naud, C., Hasch-Guichard, W., Garcia-Ripoll, J. J., Roch, N., Buisson, O.
Format: Preprint
Published: 2022
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author Dassonneville, R.
Ramos, T.
Milchakov, V.
Mori, C.
Planat, L.
Foroughi, F.
Naud, C.
Hasch-Guichard, W.
Garcia-Ripoll, J. J.
Roch, N.
Buisson, O.
author_facet Dassonneville, R.
Ramos, T.
Milchakov, V.
Mori, C.
Planat, L.
Foroughi, F.
Naud, C.
Hasch-Guichard, W.
Garcia-Ripoll, J. J.
Roch, N.
Buisson, O.
contents We demonstrate a transmon qubit readout based on the nonlinear response to a drive of polaritonic meters in-situ coupled to the qubit. Inside a 3D readout cavity, we place a transmon molecule consisting of a transmon qubit and an ancilla mode interacting via non-perturbative cross-Kerr coupling. The cavity couples strongly only to the ancilla mode, leading to hybridized lower and upper polaritonic meters. Both polaritons are anharmonic and dissipative, as they inherit a self-Kerr nonlinearity $U$ from the ancilla and effective decay $κ$ from the open cavity. Via the ancilla, the polariton meters also inherit the non-perturbative cross-Kerr coupling to the qubit. This results in a high qubit-dependent displacement $2χ> κ, ~U$ that can be read out via the cavity without causing Purcell decay. Moreover, the polariton meters, being nonlinear resonators, present bistability, and bifurcation behavior when the probing power increases. In this work, we focus on the bifurcation at low power in the few-photon regime, called the mesoscopic regime, which is accessible when the self-Kerr and decay rates of the polariton meter are similar $U\sim κ$. Capitalizing on a latching mechanism by bifurcation, the readout is sensitive to transmon qubit relaxation error only in the first tens of nanoseconds. We thus report a single-shot fidelity of 98.6 $\%$ while having an integration time of a 500 ns and no requirement for an external quantum-limited amplifier.
format Preprint
id arxiv_https___arxiv_org_abs_2210_04793
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Transmon-qubit readout using in-situ bifurcation amplification in the mesoscopic regime
Dassonneville, R.
Ramos, T.
Milchakov, V.
Mori, C.
Planat, L.
Foroughi, F.
Naud, C.
Hasch-Guichard, W.
Garcia-Ripoll, J. J.
Roch, N.
Buisson, O.
Quantum Physics
Mesoscale and Nanoscale Physics
We demonstrate a transmon qubit readout based on the nonlinear response to a drive of polaritonic meters in-situ coupled to the qubit. Inside a 3D readout cavity, we place a transmon molecule consisting of a transmon qubit and an ancilla mode interacting via non-perturbative cross-Kerr coupling. The cavity couples strongly only to the ancilla mode, leading to hybridized lower and upper polaritonic meters. Both polaritons are anharmonic and dissipative, as they inherit a self-Kerr nonlinearity $U$ from the ancilla and effective decay $κ$ from the open cavity. Via the ancilla, the polariton meters also inherit the non-perturbative cross-Kerr coupling to the qubit. This results in a high qubit-dependent displacement $2χ> κ, ~U$ that can be read out via the cavity without causing Purcell decay. Moreover, the polariton meters, being nonlinear resonators, present bistability, and bifurcation behavior when the probing power increases. In this work, we focus on the bifurcation at low power in the few-photon regime, called the mesoscopic regime, which is accessible when the self-Kerr and decay rates of the polariton meter are similar $U\sim κ$. Capitalizing on a latching mechanism by bifurcation, the readout is sensitive to transmon qubit relaxation error only in the first tens of nanoseconds. We thus report a single-shot fidelity of 98.6 $\%$ while having an integration time of a 500 ns and no requirement for an external quantum-limited amplifier.
title Transmon-qubit readout using in-situ bifurcation amplification in the mesoscopic regime
topic Quantum Physics
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2210.04793