Light-matter interactions
The interaction between light and matter provides the most controllable arena for exploring and, indeed, exploiting quantum phenomena. The mechanical properties of light provide a wide variety of possibilities and we have explored the nature of the forces on atoms, on molecules (especially chiral molecules) [9-11] and on macroscopic bodies including those with a magnetic response [12,13]. Our work with atoms, in particular, highlighted the existence of a paradoxical vacuum friction force [14].
Light carries energy and momentum but also angular momentum and helicity. It propagates, moreover, in modes with a transverse spatial structure. We have explored the natures of these [15-21] and also the roles these play in light-matter interactions [22-26].
In addition to this, we are currently exploring the physics of spon- taneously exciting photon pairs in macroscopic optical media whose material properties can be made to vary with time [27-29]. This has close links to the dynamical Casimir effect [30], where photons are excited as a consequence of moving mirror, and where we are particularly interested in the effect of back-action [31].
References
[9] Disciminatory optical force for chiral molecules, Robert P. Cameron, Stephen M. Barnett and Alison M. Yao; New Journal of Physics 16, 013020 (2014).
[10] Diffraction Gratings for Chiral Molecules and Their Applications, Robert P. Cameron, Alison M. Yao and Stephen M. Barnett; The Journal of Physical Chemistry A 118, 3472 (2014).
[11] Matter-wave grating distinguishing conservative and dissipative interactions, Robert P. Cameron, Jörg B. Götte, Stephen M. Barnett and J. P. Cotter; Physical Review A 94, 013604 (2016).
[12] Theory of radiation pressure on magneto-dielectric materials, Stephen M. Barnett and Rodney Loudon; New Journal of Physics 17, 063027 (2015).
[13] Energy conservation and the constitutive relations in chiral and non-reciprocal media, Stephen M. Barnett and Robert P. Cameron; Journal of Optics 18, 015404 (2016).
[14] Will a decaying atom feel a friction force?, Matthias Sonnleitner, Nils Trautmann and Stephen M. Barnett; Physical Review Letters 118, 053601 (2017).
[15] Optical helicity of interfering waves, Robert P. Cameron, Stephen M. Barnett and Alison M. Yao; Journal of Modern Optics 61, 25 (2014).
[16] Optical angular momentum in a rotating frame. Fiona C. Speirits, Martin P. J. Lavery, Miles J. Padgett and Stephen M. Barnett; Optics Letters, 39, 2994 (2014).
[17] Generalized ray optics and orbital angular momentum carrying beams, Václav Potoček and Stephen M. Barnett; New Journal of Physics 17, 103034 (2015).
[18] The azimuthal component of Poynting’s vector and the angular momentum of light, Robert P. Cameron, Fiona C. Speirits, Claire Gilson, L. Allen and Stephen M. Barnett; Journal of Optics 17, 125610 (2015).
[19] Spatially structured photons that travel in free space slower than the speed of light, Daniel Giovannini, Jacqueline Romero, Václav Potoček, Gergely Ferenczi, Fiona Speirits, Stephen M. Barnett, Daniele Faccio and Miles J. Padgett; Science 347, 857 (2015).
[20] On the natures of the spin and orbital parts of optical angular momentum, Stephen M. Barnett, L. Allen, Robert P. Cameron, Claire R. Gilson, Miles J. Padgett, Fiona C. Speirits and Alison M. Yao; Journal of Optics 18, 064004 (2016).
[21] Chirality and the angular momentum of light, Robert P. Cameron, Jörg B. Götte, Stephen M. Barnett and Alison M. Yao; Philosophical Transactions of the Royal Society A 375, 20150433 (2017).
[22] Rotational Doppler velocimetry to probe the angular velocity of spinning microparticles, D. B. Phillips, M. P. Lee, F. C. Speirits, S. M. Barnett, S. H. Simpson, M. P. J. Lavery, M. J. Padgett and G. M. Gibson; Physical Review A 90, 011801(R) (2014).
[23] Observation of the rotational Doppler shift of a white-light, orbital-angular-momentum-carrying beam backscattered from a rotating body, Martin P. J. Lavery, Stephen M. Barnett, Fiona C. Speirits and Miles J. Padgett; Optica 1, 1 (2014).
[24] Optical activity in the scattering of structured light, Robert P. Cameron and Stephen M. Barnett; Physical Chemistry and Chemical Physics 16, 25819 (2014).
[25] Spatially Dependent Electromagnetically Induced Transparency, N. Radwell, T. W. Clark, B. Piccirillo, S. M. Barnett and S. Franke-Arnold; Physical Review Letters 114, 123603 (2015).
[26] Chiral rotational spectroscopy, Robert P. Cameron, Jörg B. Götte and Stephen M. Barnett; Physical Review A 94, 032505 (2016).
[27] Spontaneous Photon Production in Time-Dependent Epsilon-Near-Zero Materials, Angus Prain, Stefano Vezzoli, N. Westerberg, T. Roger and D. Faccio; Phys. Rev. Lett. 118, 133904 (2017)
[28] Optical analogue of the dynamical Casimir effect in a dispersion-oscillating fibre, Stefano Vezzoli, Arnaud Mussot, Niclas Westerberg, Alexandre Kudlinski, Hatef Dinparasti Saleh, Angus Prain, Fabio Biancalana, Eric Lantz and Daniele Faccio; Nature Communications Physics 2, 84 (2019)
[29] Vacuum radiation and frequency-mixing in linear light-matter systems, Niclas Westerberg, Angus Prain, Daniele Faccio and Patrik Ohberg; J. Phys. Commun. 3 065012 (2019)
[30] G. T. Moore, Journal of Mathematical Physics 11, 2679 (1970)
[31] Mechanical backreaction effect of the dynamical Casimir emission, Salvatore Butera and Iacopo Carusotto; Phys. Rev. A 99, 053815 (2019)