Quantum Nano-Optomechanics – Q-NOM

In order to conciliate the dynamics of the qubit and the nanoresonator, we have driven a Rabi precession at a frequency close to the mechanical resonance. We have shown that one can then lock the qubit dynamics on a coherently driven mechanical motion, which allowed to investigate the coupled dynamics of both hybrid components.
We have developed optical readout techniques of the vibrations of the nanoresonator,. This 2D character allowed their use as vectorial and ultrasensitive force sensors. They have been used in particular to probe the backaction of the readout laser beam and to identify areas where the topology of the optical force field was not driving the nanowire into a dynamical instability, which was also studied. Finally, we have developed optical readout techniques in the photon counting regime, which ensures a minimal perturbation of the system, and is compatible with cryogenic environments or for investigating nanoresonators weakly coupled to the light.

We have interfaced a single spin qubit and a nanomechanical oscillator, coupled through the Zeeman Effect once immersed in a strong magnetic field gradient. We have investigated the synchronization of the spin precession on the mechanical motion assisted by microwave field. This allowed the observation of a phononic Mollow triplet, a first signature illustrating the dressing of the qubit with the phonon field. We have also developed the nano-optomechanics of the nanowires and demonstrated the possibility to map the backaction force of the laser used for optical readout, permitting to illustrate the non-conservative character of the light matter interaction.

voir le rapport final

O. Arcizet, et al, Nature Phys (2011)
First observation of a hybrid coupling between a nanomechanical oscillator and a single spin qubit.

I. Yeo, et al, Nature Nano. (2014)
Investigation of strain coupling between a quantum dot and the vibration of the supporting mechanical structure

S. Rohr, et al., Phys. Rev. Lett. (2014)
Investigation of a novel spin-locking mechanism enabled by a resonant microwave field, where the spin dynamics gets synchronized on a RF field,

A. Gloppe, et al, Nature Nano. (2014)
First report on nano-optomechanics of nanowire. Investigation of the dynamical backaction in a 2D force field and novel dynamical instability observed in regions of strong vorticity.

O. Arcizet has been recruited as a Chargé de Recherche at CNRS in the Near Field Microscopies group at Institut Néel (Grenoble) in December 2009 and starts developing his own research activities, for which financial support by the ANR is requested.
The goal of the QNAO project consists in extending the thematic of cavity optomechanics at low phonon number down to the nanoscale and observing the first quantum signatures on hybrid systems made of nanomechanical oscillators and single two-level-systems (TLS).

From their low mass and higher mechanical susceptibility, nano-resonators are ideal tools for week forces measurements. Sensitivities at the attoNewton have already been reported, which could facilitate the access to the quantum regime of radiation pressure. Such systems could be naturally exploited in solid state physics experiments at the condition to be able to detect and control their Brownian motion. To do so, an ultrasensitive optical near-field sensor of the nano-motion based on ultra high-Q optical microcavities will be developed.

The core part of the project aims at studying the coupling of a nano-resonator to a single quantum emitter: a color center in diamond, the Nitrogen Vacancy (NV) defect. These defects have been widely studied over the last decade, a consequence of their ability to generate single photons on demand and the important control gained on their electronic spin properties. Their fundamental ground state is a triplet whose spin state can be polarized and manipulated by pure optical means, and has been exploited as a quantum register demonstrating record lifetimes at room temperature.

NV centre then represents a robust quantum emitter already working in a quantum regime, whose coupling to a nanomechanical oscillator close to its motional ground state will provide a fantastic playground for hybrid quantum optomechanics. For example, in analogy with trapped ion physics, this hybrid optomechanical coupling could be exploited to cool down to the nanomechanical oscillator down to its vibrational ground state.
The goal of the project consists in observing the first quantum signatures in this new setting and studying the resonant optomechanical coupling to a single emitter. Both resonant optomechanical coupling (impulsion transfer, radiation pressure), and magnetic coupling to its electronic spin will be studied. As recently noticed, the latter could allow reaching the strong coupling regime.

Diamond nanomechanical oscillators will be specifically developed and exploited for both their superior mechanical, thermal and superconducting properties and their ability to host distinguishable NV centers that will be created within the structure.
The mechanical properties of the nanoresonators produced will be studied by means of the near field displacement sensor, while its optical and electronic spin properties will be investigated on a homebuilt confocal microscope integrating a microwave excitation for observing electronic spin resonances.

A cryogenic experiment will be developed after a pre-characterization phase, aiming at observing the first quantum signatures in this new hybrid system.

From the exponentially increasing amount of publications and the quality of the groups involved in the fields of both cavity optomechanics at low phonon number and NV physics, it is fair to say that this project is sitting at the verge of two extremely active and competitive fields of modern physic and requires a strong support from the ANR.