Cavity optomechanics: towards sensing at the quantum limit

Lead Research Organisation: University of Southampton
Department Name: School of Mathematics

Abstract

The grand challenge of attempting to cool a small mechanical device towards its quantum ground state is driving intense activity in many leading experimental groups worldwide. What seemed an unfeasible target only a decade ago, now appears tantalisingly close: by means of optomechanical techniques, micromechanical resonators such as small mirrors and cantilevers have been cooled by several orders of magnitude, down to occupation numbers of order n~30. The ultimate goal of approaching the ground state (n~1) now seems a realistic prospect, although serious obstacles remain; among these, thermal coupling to the environment is the most serious.However, within the last year, three groups (including the PI's) have independently proposed a novel scheme which has a fundamental new design: a dielectric nanosphere, optically levitated in a cavity and cooled by dipole forces arising from the optical field. The lack of mechanical connection to the cavity structure in a sense insulates the device from important sources of thermal noise and gives this scheme a unique edge in relation to conventional devices. The project brings together experimental and theory groups from London and Southampton with the ultimate goal of successfully implementing this scheme experimentally, for the first time. In addition, we aim to thoroughly understand the underlying physics theoretically by undertaking complete and realistic simulations of the optically cooled nanosphere system.Once the quantum limit is achieved, the main target is to operate the device in this regime. The rewards are potentially great. This is an attainable quantum technology which offers the prospect of unparalleled sensitivity in measurement, limited only by the Heisenberg uncertainty principle. For example, it is for this reason that these devices are used for gravitational-wave detectors, which require extraordinarily precise detections of displacement. They offer also the possibility of fundamental insights into the quantum-classical border: it may be possible to investigate superpositions which differ only by the displacement of a macroscopic object. Some experimental groups are investigating dipole-force coupling cavity optomechanics using a BEC (Bose Einstein Condensate) as the mechanical oscillator. In this case, the target is already in the ground state so it is already possible to explore the quantum regime. We will also investigate this regime theoretically, in order to establish whether quantum effects like squeezing (which improve sensing in the quantum regime) may be viably generated in such a scheme, as two of the co-applicants have already identified a potentially promising regime.Finally, taking the long view, we note that in parallel to this work, small sensors such as micron-sized cantilevers are actively being developed for biosensing applications (for ultra-sensitive detection of biomolecules or as force sensors). UCL, in particular the LCN (London Centre for Nanotechnology) is a leader in this field. On the otherhand, groups (such as the Caltech group of Vahala) working to cool optomechanical devices to the quantum limit are already testing their potential as biosensors.A desirable ambition, in the long-term would be to achieve a merger of these two directions: quantum limited detection and biosensing. We will explore the viability of employing schemes based on our dielectric nanospheres.

Publications

10 25 50
 
Description We have analysed strong coupling of electromagnetic fields to atoms and other resonator systems that can help to control light-matter interactions and nonlinearities in these systems. We have shown that the back-action of a continuous quantum measurement process can be exploited in sensing and in optical cavity systems, providing tools for quantum engineering of small systems and future quantum technologies.

More outcomes will still follow. The work has triggered several studies of cooperative phenomena for controlling cold atoms with proposals for sensing applications.
Exploitation Route The developed tools for the studies of light-matter interactions and continuous quantum measurement processes could be exploited in theoretical analysis of many-body quantum systems and, e.g., in design of quantum technologies for sensing and metrology.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Energy

URL http://www.soton.ac.uk/~janne
 
Description In the analysis of the electromagnetic response of atomic and resonator systems in experiments in Paris and in Southampton. Also to the development of cooperative phenomena for quantum sensing.
Impact Types Cultural

 
Description President's Science Awards
Geographic Reach Europe 
Policy Influence Type Gave evidence to a government review
 
Description Heidelbeg 
Organisation Heidelberg University
Country Germany 
Sector Academic/University 
PI Contribution Theoretical analysis of experimental findings
Collaborator Contribution Valuable experimental data and research time of team members
Impact Two publications PHYSICAL REVIEW A 84, 011609(R) (2011) New Journal of Physics 15 (2013) 063035
Start Year 2009
 
Description paris 
Organisation L'Institut d'Optique Graduate School
Country France 
Sector Academic/University 
PI Contribution Theoretical analysis of experimental findings
Collaborator Contribution valuable experimental data and research team time
Impact Publication: Physical Review Letters 113, 133602 (2014)
Start Year 2013
 
Description Chairing a session at Longrange 2014, Palaiseau, Paris, France 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Expert conference/workshop
Year(s) Of Engagement Activity 2014
 
Description Invited Talk - Long-range, Ercolano, Naples, Italy 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact One of the main meetings in the research topic of long-range interactions
Year(s) Of Engagement Activity 2016
URL http://www.erbium.at/longrange/
 
Description Invited Talk - Quantum Metamaterials, Spetses, Greece 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact International workshop including a cross-disciplinary audience
Year(s) Of Engagement Activity 2016
URL https://qcn.physics.uoc.gr/qmm2016/
 
Description Invited Talk - workshop on Quantum and Topological Nanophotonics, Singapore 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A high profile workshop with invited speakers around the world
Year(s) Of Engagement Activity 2016
URL http://cdpt.ntu.edu.sg/Pages/QTN_2016.html
 
Description Invited talk Nonequilibrium quantum dynamics in low dimensions, Durham 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited talk for an expert audience
Year(s) Of Engagement Activity 2015
 
Description Invited talk Winter Colloquium on the Physics of Quantum Electronics, Utah, USA 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Specialist conference
Year(s) Of Engagement Activity 2016
 
Description Invited talk Workshop on Cooperative scattering Porquerolles, France 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Expert meeting
Year(s) Of Engagement Activity 2014