Quantum dynamics of a high-finesse optical cavity coupled with a thin semi-transparent membrane (original) (raw)
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Physical Review A, 2011
We study the quantum dynamics of the cavity optomechanical system formed by a Fabry-Perot cavity with a thin vibrating membrane at its center. We first derive the general multimode Hamiltonian describing the radiation pressure interaction between the cavity modes and the vibrational modes of the membrane. We then restrict the analysis to the standard case of a single cavity mode interacting with a single mechanical resonator and we determine to what extent optical absorption by the membrane hinder reaching a quantum regime for the cavity-membrane system. We show that membrane absorption does not pose serious limitations and that one can simultaneously achieve ground state cooling of a vibrational mode of the membrane and stationary optomechanical entanglement with state-of-the-art apparatuses.
Quantum dynamics of a vibrational mode of a membrane within an optical cavity
2010
Optomechanical systems are a promising candidate for the implementation of quantum interfaces for storing and redistributing quantum information. Here we focus on the case of a high-finesse optical cavity with a thin vibrating semitransparent membrane in the middle. We show that robust and stationary optomechanical entanglement could be achieved in the system, even in the presence of nonnegligible optical absorption in the membrane. We also present some preliminary experimental data showing radiation-pressure induced optical bistability.
Atom-membrane cooling and entanglement using cavity electromagnetically induced transparency
Physical Review A, 2011
We investigate a hybrid optomechanical system comprised of a mechanical oscillator and an atomic 3-level ensemble within an optical cavity. We show that a suitably tailored cavity field response via Electromagnetically Induced Transparency (EIT) in the atomic medium allows for strong coupling of the mechanical mirror oscillations to the collective atomic ground-state spin. This facilitates ground-state cooling of the mirror motion, quantum state mapping and robust atom-mirror entanglement even for cavity widths larger than the mechanical oscillator frequency. PACS numbers: 03.67.Bg,42.50.Gy,42.50.Lc,85.85.+j The past years have witnessed tremendous progress towards the control of mechanical motion at the quantum limit in micro-and nano-optomechanical systems . While cavity optomechanical phenomena are traditionally investigated with solid-state optomechanical systems -micromirrors, cantilever tips, toroidal resonators, movable membranes, etc. -cold atomic gasses placed in high-finesse optical cavities [2] have also successfully been used to implement equivalent Hamiltonians at ultralow temperatures. Consequently, several proposals suggested a combination of both approaches to realize hybrid optomechanical systems , in which well-controlled atomic systems can be interfaced with solid-state mechanical resonators. These can benefit from the well-established atomic physics toolbox for cooling, trapping, state preparation, control and readout and allow to properly tailor the atomcavity response function.
Dispersive optomechanics: a membrane inside a cavity
New Journal of Physics, 2008
We present the results of theoretical and experimental studies of dispersively coupled (or 'membrane in the middle') optomechanical systems. We calculate the linear optical properties of a high finesse cavity containing a thin dielectric membrane. We focus on the cavity's transmission, reflection and finesse as a function of the membrane's position along the cavity axis and as a function of its optical loss. We compare these calculations with measurements and find excellent agreement in cavities with empty-cavity finesses in the range 10 4-10 5. The imaginary part of the membrane's index of refraction is found to be ∼10 −4. We calculate the laser cooling performance of this system, with a particular focus on the less-intuitive regime in which photons 'tunnel' through the membrane on a timescale comparable to the membrane's period of oscillation. Lastly, we present calculations of quantum non-demolition measurements of the membrane's phonon number in the low signal-to-noise regime where the phonon lifetime is comparable to the QND readout time.
Journal of Physics B: Atomic, Molecular and Optical Physics, 2011
We propose a theoretical scheme to show the possibility of generating motional nonlinear coherent states and their superposition for an undamped vibrating micromechanical membrane inside an optical cavity. The scheme is based on an intensity-dependent coupling of the membrane to the radiation pressure field. We show that if the cavity field is initially prepared in a Fock state, the motional state of the membrane may evolve from vacuum state to a special type of nonlinear coherent states. By examining the nonclassical properties of the generated state of the membrane, including the quadrature squeezing and the sub-Poissonian statistics, we find that by varying the Lamb-Dicke parameter and the membrane's reflectivity one can effectively control those properties. In addition, the scheme offers the possibility of generating various types of the so-called nonlinear multicomponent Schrödinger cat sates of the membrane. We also examine the effect of the damping of the cavity field on the motional state of the membrane. and entanglement at a macroscopic scale .
Cavity-enhanced long-distance coupling of an atomic ensemble to a micromechanical membrane
Physical Review A, 2013
We discuss a hybrid quantum system where a dielectric membrane situated inside an optical cavity is coupled to a distant atomic ensemble trapped in an optical lattice. The coupling is mediated by the exchange of sideband photons of the lattice laser, and is enhanced by the cavity finesse as well as the square root of the number of atoms. In addition to observing coherent dynamics between the two systems, one can also switch on a tailored dissipation by laser cooling the atoms, thereby allowing for sympathetic cooling of the membrane. The resulting cooling scheme does not require resolved sideband conditions for the cavity, which relaxes a constraint present in standard optomechanical cavity cooling. We present a quantum mechanical treatment of this modular open system which takes into account the dominant imperfections, and identify optimal operation points for both coherent dynamics and sympathetic cooling. In particular, we find that ground state cooling of a cryogenically pre-cooled membrane is possible for realistic parameters.
Physical Review A
We propose how to achieve significantly enhanced quantum refrigeration and entanglement by coupling a pumped auxiliary cavity to an optomechanical cavity. We obtain both analytical and numerical results and find optimal-refrigeration and-entanglement conditions under the auxiliary-cavity-assisted (ACA) mechanism. Our method leads to a significant amplification in the net refrigeration rate and reveals that the ACA entanglement has a much stronger noise robustness in comparison with the unassisted case. By appropriately designing the ACA mechanism, an effective mechanical susceptibility can be well adjusted, and a genuine tripartite entanglement of cooling-cavity photons, auxiliary-cavity photons, and phonons can be generated. Specifically, we show that both optomechanical refrigeration and entanglement can be greatly enhanced for the blue-detuned driving of the auxiliary cavity but suppressed for the red-detuned case. Our work paves a way towards further quantum control of macroscopic mechanical systems and the enhancement and protection of fragile quantum resources.
Quantum Effects in Optomechanical Systems
Advances in Atomic, Molecular, and Optical Physics, Vol 57, 2009
The search for experimental demonstrations of the quantum behavior of macroscopic mechanical resonators is a fastly growing field of investigation and recent results suggest that the generation of quantum states of resonators with a mass at the microgram scale is within reach. In this chapter we give an overview of two important topics within this research field: cooling to the motional ground state, and the generation of entanglement involving mechanical, optical and atomic degrees of freedom. We focus on optomechanical systems where the resonator is coupled to one or more driven cavity modes by the radiation pressure interaction. We show that robust stationary entanglement between the mechanical resonator and the output fields of the cavity can be generated, and that this entanglement can be transferred to atomic ensembles placed within the cavity. These results show that optomechanical devices are interesting candidates for the realization of quantum memories and interfaces for continuous variable quantum communication networks.
Optomechanical Entanglement between a Movable Mirror and a Cavity Field
Physical Review Letters, 2007
We show how stationary entanglement between an optical cavity field mode and a macroscopic vibrating mirror can be generated by means of radiation pressure. We also show how the generated optomechanical entanglement can be quantified and we suggest an experimental readout-scheme to fully characterize the entangled state. Surprisingly, such optomechanical entanglement is shown to persist for environment temperatures above 20K using state-of-the-art experimental parameters.