Off-resonance coupling between a cavity mode and an ensemble of driven spins

Abstract

We study the interaction between a superconducting cavity and a spin ensemble. The response of a cavity mode is monitored while simultaneously the spins are driven at a frequency close to their Larmor frequency, which is tuned to a value much higher than the cavity resonance. We experimentally find that the effective damping rate of the cavity mode is shifted by the driven spins. The measured shift in the damping rate is attributed to the retarded response of the cavity mode to the driven spins. The experimental results are compared with theoretical predictions and fair agreement is found.

Instability in the Hartmann--Hahn double resonance

“…The experimental feasibility of reaching this instability region is discussed. Related effects of Sisyphus cooling, amplification, lasing and SEO have been theoretically predicted in other systems having a similar retarded response [8][9][10][11][12][13].…”

“…In practice, the value of the NV transition frequency ω a0 (which can be tuned by the externally applied magnetic field) is limited due to the HH matching condition by the maximum possible value of the driving amplitude ω b1 that can be experimentally achieved. For the case where a high quality factor microwave resonator is employed for driving the P1 spins [13], a value of about ω a0 = ω R ≃ 2π × 50 MHz, is reachable. This value is too small to allow making |P az,s | becoming of order unity using cooling only.…”

“…For that case spin 'a' is assumed to be a nuclear spin and spin 'b' is an electron spin. For example, for the case of P1 defects in diamond, the dipolar coupling between the nitrogen 14 nuclear spin S = 1 and the spin of the localized unpaired electron occupying the same lattice site gives rise to hyperfine splitting on the order of 100 MHz [13]. Such a coupling is sufficiently strong to make the region of SEO experimentally accessible, and the study of this instability can be performed using measurements of ensembles containing many P1 defects.…”

Phononic Josephson oscillation and self-trapping with two-phonon exchange interaction

“…Our results open a way to investigate interferometer and Bose-Hubbard model with two-phonon exchange interactions in optomechanical systems. Similarly, BJJ based on two-boson exchange interaction can also be realized in the optical and microwave systems [27][28][29][30][31][32][33].…”

“…In contrast to all hitherto realized BJJs, where two nonlinear bosonic systems are coupled by hopping of single bosons, we here propose a BJJ in two nonlinear mechanical modes coupled through two-phonon exchange interaction. The Bose-Hubbard model with atom-pair tunneling [22][23][24][25][26] or twophoton exchange [27][28][29][30][31][32][33] has been studied for years. However, the realization of two-phonon exchange interaction in the mechanical systems is still lack of effective method.…”