Ground state cooling of nanomechanical resonator via linear coupling in a superconducting circuit

Anjan Samanta

Lin Tian

We present a cooling mechanism for a nanomechanical resonator that linearly couples with a LC oscillator. The linear coupling, when periodically modulated at red detuning, up-converts the low-frequency nanomechanical quanta to the high-frequency LC oscillator quanta which then dissipates in the circuits via the damping of the LC oscillator. We show that realistic circuit can be designed in the superconducting system to implement this scheme in the resolved-sideband regime and reach the quantum ground state of the nanomechanical mode. A detailed study of the origin of the quantum back-action noise in this cooling process is also presented.

Keyu Xia, Jörg Evers

Ground state cooling of a nanomechanical resonator coupled to a superconducting flux qubit is discussed. By inducing quantum interference to cancel unwanted heating excitations, ground state cooling becomes possible in the nonresolved regime. The qubit is modeled as a three-level system in Lambda configuration, and the driving fluxes are applied such that the qubit absorption spectrum exhibits electromagnetically induced transparency, thereby canceling the unwanted excitations. As our scheme allows the application of strong cooling fields, fast and efficient cooling can be achieved.

Y. L. Hao, Francisco P. M. Rouxinol, Seung‐Bo Shim +1 more

K. Jähne, Klemens Hammerer

Abstract. In this paper we present a scheme for ground state cooling of a flexural mode of a nanomechanical beam incorporated in a loop-shaped Cooper-pair box (CPB) circuit. Via the Lorentz force coupling of the beam motion to circulating CPB-circuit currents, energy is transferred to the CPB qubit which acts as a dissipative two-level system. The cooling process is driven by a detuned gate-voltage drive acting on the CPB. We analyze the cooling force spectrum and present analytical expressions for the cooling rate and final occupation number for a wide parameter regime. In particular, we find that cooling is optimized in a strong drive regime, and we present the necessary conditions for ground-state cooling. PACS numbers: 85.25.-j, 85.85.+j, 37.10.RsGround state cooling of a nanomechanical resonator via a Cooper pair box qubit 2

Akshay K. Naik, O. Buu, Matthew LaHaye +4 more