Entangled-state generation and Bell inequality violations in nanomechanical resonators

Abstract

We investigate theoretically the conditions under which a multi-mode nanomechanical resonator, operated as a purely mechanical parametric oscillator, can be driven into highly nonclassical states. We find that when the device can be cooled to near its ground state, and certain mode matching conditions are satisfied, it is possible to prepare distinct resonator modes in quantum entangled states that violate Bell inequalities with homodyne quadrature measurements. We analyze the parameter regimes for such Bell inequality violations, and while experimentally challenging, we believe that the realization of such states lies within reach. This is a re-imagining of a quintessential quantum optics experiment by using phonons that represent tangible mechanical vibrations.

Generation and detection of large and robust entanglement between two different mechanical resonators in cavity optomechanics

“…A similar strategy has been provided to enhance the entanglement of two MRs [28]. More recent proposal applied reservoir engineering ideas [29-33] to optomechanical scenarios, by exploiting suitable multifrequency drivings and optical architectures in order to achieve more robust generation of steady state entanglement between two MRs [34-40], eventually profiting from mechanical nonlinearities and/or parametric driving [41,42].In the present paper we propose a novel optomechanical/electromechanical scheme for the generation of remarkably large CV entanglement between two MRs with different frequencies, which is also extremely robust with respect to thermal noise. The scheme is particularly simple, involving only a single, bichromatically-driven, optical cavity mode, and optimally works in a rotating wave approximation (RWA) regime where counterrotating, non-resonant, terms associated with the bichromatic driving are negligible.…”

Testing Bell’s inequality with one-party weak measurements

“…In particular, experimental tests typically comprise a source of entangled particles (usually photons produced by atomic cascade [5][6][7] or spontaneous parametric down conversion [8,11]. However, some interesting nonlocality tests have been recently proposed with superconducting circuits [12][13][14][15]) that are sent to two distant observers who independently perform measurements in a number of settings and compare their results a posteriori. It is assumed that the outcome of each measurement reveals an unbiased physical property of the system and that measurements made by one observer have no effect on the measurements performed by the other.…”

The Test of Entanglement of Polarization States of a Semi-Classical Optical Parametric Oscillator

“…The multipartite nature of entanglement was verified by evaluating the van Loock-Furusawa criterion for a particular set of entanglement witnesses deduced from physical considerations [9]. Johansson R. (2014) [10] investigated theoretically the conditions under which a multi-mode nano-mechanical resonator, operating as a purely mechanical parametric oscillator, can be driven into highly non-classical states. Quantum entangled states of the system violate Bell inequalities with homodyne quadrature measurements.…”