We investigate nonequilibrium energy transport and nonclassical correlations of photons in a nonequilibrium two-mode circuit quantum electrodynamic system with noncommutative qubit-photon couplings. Our calculations include a quantum master equation, which can handle ultrastrong qubit-photon interactions. For weak qubit-photon couplings, the nonmonotonic behavior of nonequilibrium energy flow is explored for large temperature bias, stemming from the breakdown of microscopic energy transition cycles. Two distinct scaling features of the coupling parameters in energy currents are analytically shown. Moreover, the longitudinal qubit-photon coupling shows a dramatic contribution to the exhibition of antibunching behaviors of autocorrelation and violation of the Cauchy-Schwarz inequality of the cross correlation of photons. These results may provide insight into quantum energy modulation devices and photon correlation manipulation in circuit quantum electrodynamics.We investigate nonequilibrium energy transport and nonclassical correlations of photons in a nonequilibrium two-mode circuit quantum electrodynamic system with noncommutative qubit-photon couplings. Our calculations include a quantum master equation, which can handle ultrastrong qubit-photon interactions. For weak qubit-photon couplings, the nonmonotonic behavior of nonequilibrium energy flow is explored for large temperature bias, stemming from the breakdown of microscopic energy transition cycles. Two distinct scaling features of the coupling parameters in energy currents are analytically shown. Moreover, the longitudinal qubit-photon coupling shows a dramatic contribution to the exhibition of antibunching behaviors of autocorrelation and violation of the Cauchy-Schwarz inequality of the cross correlation of photons. These results may provide insight into quantum energy modulation devices and photon correlation manipulation in circuit quantum electrodynamics.

Physical Review AOct 15, 20240 citations

Multi-qubit circuit quantum electrodynamics

Oliver Viehmann

Jan 1, 20130 citations

Circuit quantum electrodynamics with a spin qubit

Karl D. Petersson, Louis W. McFaul, Michael D. Schroer +4 more

arXiv:1205.6767NatureOct 1, 2012463 citations

High-impedance superconducting resonators and on-chip filters for circuit quantum electrodynamics with semiconductor quantum dots

X. Zhang, Zhiyong Zhu, N. Phuan Ong +1 more

Spin-photon coupling presents an enticing opportunity for the long-range coupling of spin qubits. The spin-photon coupling rate, ${g}_{s}$ , is proportional to the charge-photon coupling rate, ${g}_{c}$ . To move deeper into the strong-coupling regime, ${g}_{c}$ can be enhanced by fabricating high-impedance cavities using high-kinetic-inductance films. Here, we report dc transport and microwave response investigations of niobium nitride ( $\mathrm{Nb}\mathrm{N}$ ) films of different thicknesses. The kinetic inductance increases rapidly as the film thickness is reduced below 50 nm and for 15-nm $\mathrm{Nb}\mathrm{N}$ films we measure a sheet kinetic inductance ${L}_{k,S}=41.2\phantom{\rule{0.2em}{0ex}}\text{pH}/◻$ . As an application of the high-kinetic-inductance films, we fabricate compact $LC$ filters that are commonly used to reduce microwave leakage in circuit quantum electrodynamics (cQED) devices. These filters feature up to 60 dB of attenuation near typical cavity resonance frequencies of ${f}_{c}=8$ GHz.Spin-photon coupling presents an enticing opportunity for the long-range coupling of spin qubits. The spin-photon coupling rate, ${g}_{s}$, is proportional to the charge-photon coupling rate, ${g}_{c}$. To move deeper into the strong-coupling regime, ${g}_{c}$ can be enhanced by fabricating high-impedance cavities using high-kinetic-inductance films. Here, we report dc transport and microwave response investigations of niobium nitride ($\mathrm{Nb}\mathrm{N}$) films of different thicknesses. The kinetic inductance increases rapidly as the film thickness is reduced below 50 nm and for 15-nm $\mathrm{Nb}\mathrm{N}$ films we measure a sheet kinetic inductance ${L}_{k,S}=41.2\phantom{\rule{0.2em}{0ex}}\text{pH}/◻$. As an application of the high-kinetic-inductance films, we fabricate compact $LC$ filters that are commonly used to reduce microwave leakage in circuit quantum electrodynamics (cQED) devices. These filters feature up to 60 dB of attenuation near typical cavity resonance frequencies of ${f}_{c}=8$ GHz.

arXiv:2306.16499Physical Review AppliedJan 11, 20248 citations

Spin-photon coupling presents an enticing opportunity for the long-range coupling of spin qubits. The spin-photon coupling rate,

{g}_{s}

, is proportional to the charge-photon coupling rate,

{g}_{c}

. To move deeper into the strong-coupling regime,

{g}_{c}

can be enhanced by fabricating high-impedance cavities using high-kinetic-inductance films. Here, we report dc transport and microwave response investigations of niobium nitride (

\mathrm{Nb}\mathrm{N}

) films of different thicknesses. The kinetic inductance increases rapidly as the film thickness is reduced below 50 nm and for 15-nm

\mathrm{Nb}\mathrm{N}

films we measure a sheet kinetic inductance

{L}_{k,S}=41.2\phantom{\rule{0.2em}{0ex}}\text{pH}/◻

. As an application of the high-kinetic-inductance films, we fabricate compact

LC

filters that are commonly used to reduce microwave leakage in circuit quantum electrodynamics (cQED) devices. These filters feature up to 60 dB of attenuation near typical cavity resonance frequencies of

{f}_{c}=8

GHz.