André Xuereb

Strong Coupling and Long-Range Collective Interactions in Optomechanical Arrays

We investigate the collective optomechanics of an ensemble of scatterers inside a Fabry-Pérot resonator and identify an optimized configuration where the ensemble is transmissive, in contrast to the usual reflective optomechanics approach. In this configuration, the optomechanical coupling of a specific collective mechanical mode can be several orders of magnitude larger than the single-element case, and long-range interactions can be generated between the different elements since light permeates throughout the array. This new regime should realistically allow for achieving strong single-photon optomechanical coupling with massive resonators, realizing hybrid quantum interfaces, and exploiting collective long-range interactions in arrays of atoms or mechanical oscillators.

Perspective on quantum thermodynamics

We are grateful for discussions with Janet Anders, Lidia del Rio, and Mathis Friesdorf. JM would like to acknowledge support from the Marie Sklodowska-Curie Action H2020-MSCA-IF-2014. This work was partly supported by the European COST network MP1209.

Dissipative Optomechanics in a Michelson{Sagnac Interferometer

Dissipative optomechanics studies the coupling of the motion of an optical element to the decay rate of a cavity. We propose and theoretically explore a realization of this system in the optical domain, using a combined Michelson-Sagnac interferometer, which enables a strong and tunable dissipative coupling. Quantum interference in such a setup results in the suppression of the lower motional sideband, leading to strongly enhanced cooling in the non-sideband-resolved regime. With state-of-the-art parameters, ground-state cooling and low-power quantum-limited position transduction are both possible. The possibility of a strong, tunable dissipative coupling opens up a new route towards observation of such fundamental optomechanical effects as nonlinear dynamics. Beyond optomechanics, the suggested method can be readily transferred to other setups involving nonlinear media, atomic ensembles, or single atoms.

Scattering theory of cooling and heating in optomechanical systems

We present a one-dimensional scattering theory which enables us to describe a wealth of effects arising from the coupling of the motional degree of freedom of scatterers to the electromagnetic field. Multiple scattering to all orders is taken into account. The theory is applied to describe the scheme of a Fabry-Perot resonator with one of its mirrors moving. The friction force, as well as the diffusion, acting on the moving mirror is derived. In the limit of a small reflection coefficient, the same model provides for the description of the mechanical effect of light on an atom moving in front of a mirror

Reconfigurable long-range phonon dynamics in optomechanical arrays.

We investigate periodic optomechanical arrays as reconfigurable platforms for engineering the coupling between multiple mechanical and electromagnetic modes and for exploring many-body phonon dynamics. Exploiting structural resonances in the coupling between light fields and collective motional modes of the array, we show that tunable effective long-range interactions between mechanical modes can be achieved. This paves the way towards the implementation of controlled phononic walks and heat transfer on densely connected graphs as well as the coherent transfer of excitations between distant elements of optomechanical arrays.

Assessing the Nonequilibrium Thermodynamics in a Quenched Quantum Many-Body System via Single Projective Measurements

The authors are indebted to T. S. Batalhao, J. Goold, R. Serra, and Peter Talkner for invaluable discussions.

Multipartite optomechanical entanglement from competing nonlinearities

A.X. acknowledges financial support from the Royal Commission for the Exhibition of 1851. M.B. was supported by a FASTQUAST ITN Marie Curie fellowship. M.P. was supported by the UK EPSRC through a Career Acceleration Fellowship and the “New Directions for EPSRC Research Leaders” initiative (EP/G004759/1).

Selectable linear or quadratic coupling in an optomechanical system

A.X. thanks the Royal Commission for the Exhibition of 1851 for financial support. M.P. is supported by the UK EPSRC through a Career Acceleration Fellowship and the “New Directions for EPSRC Research Leaders” initiative (EP/G004759/1). Parts of the calculations were carried out using computational facilities funded by the European Regional Development Fund, Project ERDF-080.

Optomechanical cooling with generalized interferometers

The fields in multiple-pass interferometers, such as the Fabry-Pérot cavity, exhibit great sensitivity not only to the presence but also to the motion of any scattering object within the optical path. We consider the general case of an interferometer comprising an arbitrary configuration of generic beam splitters and calculate the velocity-dependent radiation field and the light force exerted on a moving scatterer. We find that a simple configuration, in which the scatterer interacts with an optical resonator from which it is spatially separated, can enhance the optomechanical friction by several orders of magnitude.

Collectively enhanced optomechanical coupling in periodic arrays of scatterers

We acknowledge support from the Royal Commission for the Exhibition of 1851 (A.X.), the Austrian Science Fund (FWF) (Grant No. P24968-N27), an STSM grant from the COST Action MP1006 “Fundamental Problems in Quantum Physics” (C.G.), the EU CCQED and PICC projects, and the Danish Council for Independent Research under the Sapere Aude program (A.D.).We would also like to thank J. Bateman, K. Hammerer, I. D. Leroux, M. Paternostro, and H. Ritsch for fruitful discussions.