Research

We use 4-wave mixing in a rubidium vapour to generate beams that are entangled in their quadratures as well as in their transverse spatial degrees of freedom. These light fields, dubbed "quantum images", have subtle quantum correlations in their phases and their amplitudes that depend on the position in their transverse profiles. They could be used for the imaging of hard to see (transparent) objects, accurate beam positioning, or quantum cryptography.

 

 

The level diagram of 85Rb, in (a), used to generate the probe (Pr) and conjugate (C) beams by four-wave-mixing process (4WM). The geometry of the nonlinear 4WM interaction, in (b), shows the generation of entangled images using a mask in the input probe beam.

 

We have recently generated squeezed light beam that displays noise lower than the shot noise in 75 independent regions or “locales” along its transverse profile [3]. This localised multi-spatial-mode (MSM) quadrature squeezing can be used to improve resolution of optical imaging

 

 

The homodyne detection of the MSM quadrature squeezing works by scanning the position of the local oscillator (LO). This allows the mode structure mapping of the MSM squeezed vacuum.

 

 

Observation of localised quadrature squeezing for two orthogonal scans of the LO positions (left and right). The squeezing as a function of the LO position is shown in (a) and (d) for two diameters of the LO beam, circles (narrower LO) and squares (wider LO). The images in (b) and (e) correspond to the squares and circles in the graph.

References:

1. C. S. Embrey, J. Hordell , P. G. Petrov, and V. Boyer, Optics Express, 24, 27298–27308, (2016). doi:10.1364/OE.24.027298
2. X. Zang, J. Yang, R. Faggiani, C. Gill, P. G. Petrov, J-P. Hugonin, K. Vynck, S. Bernon, P. Bouyer, V. Boyer, and P. Lalanne, Phys. Rev. Applied , 5, 024003, (2016). doi: 10.1103/PhysRevApplied.5.024003
3. C. S. Embrey, M. T. Turnbull, P. G. Petrov, and V. Boyer, Phys. Rev. X, 5, 031004, (2015). doi:10.1103/PhysRevX.5.031004
4. M. T. Turnbull, P. G. Petrov, C. S. Embrey, A. M. Marino, and V. Boyer, Phys. Rev. A, 88, 033845, (201doi: 10.1103/PhysRevA.88.033845
5. A. M. Marino, R. C. Pooser, V. Boyer, and P. D. Lett, Nature 457, 859-862 (2009) doi:10.1038/nature07751;

Contact:
Dr Vincent Boyer - contact
Dr Plamen Petrov - contact

Our research focuses on performing precision inertial sensing, and in particular on the measurement of gravity and gravity gradients, through atom interferometry. A large portion of our work involves bringing cold atom based gravity sensing to practical use, through improving the readiness, developing the underpinning hardware, and building demonstrators that can operate in application relevant environments – for example, targeting finding underground infrastructure using a cold atom gradiometer. We are the gravity sensing team of the UK National Quantum Technology Hub in Sensors and Metrology, and are leading in transferring knowledge and capability into industry to build up impact across a variety of potential end uses, such as within civil engineering or archaeology. Our work includes a variety of projects, ranging from those performing fundamental research aiming to improve the underpinning techniques to a cross-over between physics and engineering, and those in strong collaboration with industry.

Cold Atom Interferometry Group mini-site

Contact:

Prof. Kai Bongs - contact
Dr Michael Holynski - contact

Contact:
Prof. Kai Bongs - contact
Dr Yeshpal Singh - contact