December 2014: Our joint work with the groups of Hyunseok Jeong in Korea, and Tim Ralph in Australia, has been published in JOSA B 31, 3057. We investigate how to experimentally detect a recently proposed measure to quantify macroscopic quantum superpositions [Phys. Rev. Lett. 106, 220401 (2011)], namely, “macroscopic quantumness” I. Schemes based on overlap measurements for harmonic oscillator states and for qubit states are extensively investigated. Effects of detection inefficiency and coarse-graining are analyzed in order to assess feasibility of the schemes.

September 2014: Jirawat and Tian Feng graduates of Cavendish and DAMTP Cambridge joined the group as PhD students. Welcome guys!

August 2014:Dimitris has been nominated for the Management Committee of the EU COST Action “Nanoscale Quantum Optics” 2014-2018

MPNS COST Action MP1403Nanoscale Quantum Optics

The investigation of quantum phenomena in nanophotonics systems may lead to new scales of quantum complexity and constitutes the starting point for developing photonic technologies that deliver quantum-enhanced performances in real-world situations. This ambition demands new physical insight as well as cutting-edge engineering, with an interdisciplinary approach and a view towards how such groundbreaking technologies may be implemented and commercialized. The Action aims at promoting and coordinating forefront research in nanoscale quantum optics (NQO) through a competitive and organized network, which will define new and unexplored pathways for deploying quantum technologies in nanophotonics devices within the European research area. The main vision is to establish a fruitful and successful interaction among scientists and engineers from academia, research centers and industry, focusing on quantum science & technology, nanoscale optics & photonics, and materials science. The Action will address fundamental challenges in NQO, contribute to the discovery of novel phenomena and define new routes for applications in information & communication technology, sensing & metrology, and energy efficiency. Gathering a critical mass of experts the Action will serve as a platform in NQO and as such it will cooperate with industry and academia to promote innovation and education in a forefront research field.

July 2014: Our work on “Probing the topological properties of the Jackiw-Rebbi model with light” has been accepted in Nature Scientific Reports 4, 6110 (2014)

The Jackiw-Rebbi model describes a one-dimensional Dirac particle coupled to a soliton field and can be equivalently thought of as the model describing a Dirac particle with a spatially dependent mass term. Neglecting the dynamics of the soliton field, a kink in the background soliton profile yields a topologically protected zero-energy mode for the particle, which in turn leads to charge fractionalization. We show here that the model, in the first quantised form, can be realised in a driven slow-light setup, where photons mimic the Dirac particles and the soliton field can be implemented–and tuned–by adjusting optical parameters such as the atom-photon detuning. Furthermore, we discuss how the existence of the zero-mode, and its topological stability, can be probed naturally by analyzing the transmission spectrum. We conclude by analyzing the robustness of our approach against possible experimental errors in engineering the Jackiw-Rebbi Hamiltonian in this optical setup.

(Left): Schematic diagram of the linear slow light system required. Lightis interfaced with an ensemble of atoms where propagating light fields $\mathcal{E}_1$ and $\mathcal{E}_2$ play the role of Dirac spinor components. By adjusting the relevant optical couplings and detunings, the J-R model can be simulated and its topological aspects probed by looking at the transmission spectrum. (b) The reflection $|R|^{2}$ (black) and transmission $|T|^{2}$ (red) curves for the effective Dirac particle (a) without the soliton background and (b) with a soliton field whose profile is $0.25 \tanh(0.02 z)$. (a) shows the Dirac mass bandgap whereas (b) shows near-unity transmission near the zero-energy due to the bound zero-mode.

April 2013: Out work on “Experimental simulation of charge conservation violation and Majorana dynamics” is out, for a preprint in pdf click arXiv:1404.5444

Unphysical particles are commonly ruled out from the solution of physical equations, as they fundamentally cannot exist in any real system and, hence, cannot be examined experimentally in a direct fashion. One of the most celebrated equations that allows unphysical solutions is the relativistic Majorana equation which might describe neutrinos and other exotic particles beyond the Standard Model. The equation’s physical solutions, the Majorana fermions, are predicted to be their own anti-particles and as a consequence they have to be neutrally charged; the charged version however (called Majoranon) is, due to charge non-conservation, unphysical and cannot exist. On

the other hand, charge conservation violation has been contemplated in alternative theories associated with higher spacetime dimensions or a non-vanishing photon mass; theories whose exotic nature makes experimental testing with current technology an impossible task.

In our work, we experimentally implement a simulation of the Majorana equation and study the dynamics of its hypothetical particle solution, the Majoranon. For this we exploit the fact that in quantum mechanics the wave function itself is not a measurable quantity. Therefore, wave functions of real physical particles, in our case Dirac particles with opposite masses, can be superposed to a wave function of an unphysical particle, the Majoranon. In our experiment each Dirac particle is simulated by photon pulses propagating in specifically designed optical waveguide lattices reproducing the necessary relativistic dynamics. After a predefined evolution length the two lattices are recombined and the evolution of the Majoranon wave function can be inferred from measurable intensities of the output light. Input state preparation, evolution and read-out are all realised within one compact optical chip. We observe the strong impact of the charge conjugation operation on the dynamics of the simulated particle. In particular, we show that a characteristic quantity corresponding to the pseudo-energy of a Dirac-system behaves very differently in the Majorana-system: the latter displays a full-oscillation between the spinor components unlike the former.

Besides such specific observations of the exotic Majorana dynamics, our results represent the first implementation of a simulator for an unphysical phenomenon. We anticipate our findings to open the field of quantum simulation of exotic particles beyond the Standard Model and to substantially widen the scope of future investigations with respect to yet unknown benefits from unphysical operations in areas such as quantum information processing.

March 2013: Dimitris has been invited to talk about our work on quantum simulations with hybrid light-matter systems to the following international conferences.

Control of Quantum Dynamics of Atoms, Molecules and Ensembles by Light Workshop 2014, Bulgaria, 23-27 June 2014

META’14, the 5th International Conference on Metamaterials, Photonic Crystals and Plasmonics , Singapore, 20-23 May.

Advanced Workshop on Landau-Zener Interferometry and Quantum Control in Condensed Matter, ICTP workshop, Smyrna, Turkey, 29 September-3 October

23rd Annual International Laser Physics Workshop, Sofia, Bulgaria July 14-18

February 2013: Our paper on “Probing the effect of interaction in Anderson localization using linear photonic lattices” has been published in Physical Review A

January 2014: Dimitris is invited to join the editorial board of European Physical Journal-Quantum Technology by Springer

December 2013: Dr Ping Nang Ma from ETH, joined our group as postdoctoral research fellow. Welcome to the groupTama!

October 2013: Special issue on “Quantum simulations” in Springer EPJ Quantum Technology is accepting submissions! Guest edited by D.G. Angelakis, D. Jaksch, A. Aspuru-Guzik and E. Solano. Topics include both theoretical and experimental aspects of quantum simulations. Accepting submissions now until June 1st 2014!

September 2013: Coverage of our recent work in local and national newpapers (in Greek), ΕΛΕΥΘΕΡΟΤΥΠΙΑ , ΕΦΗΜΕΡΙΔΑ ΤΩΝ ΣΥΝΤΑΚΤΩΝ, ΧΑΝΙΩΤΙΚΑ

August 2013: Our works on “ Robust-to-loss entanglement generation using a quantum plasmonic nanoparticle array ” and “Realizing the driven non-linear Schrodinger equation with stationary light” have been published in New Journal of Physics and accepted in Europhysics Letters.

June 2013: The Benasque workshop on Quantum Simulators 2013 is announced, Dimitris will be giving a invited talk, check here for the program details

May 2013: Nikos has finished his first paper, a collaboration with Oxford on “Frozen photons in Jaynes-Cummings arrays”. arXiv:arXiv:1305.6576. Well done Nikos!

May 2013: MingXia, our first CQT PhD student, has finished and submitted her PhD thesis on “Quantum simulations with photons in nonlinear optical waveguides”. Well done MingXia!

April 2013: Our work on “Proposal for simulating the Majorana equation in tabletop experiment has been published” as Phys. Rev. A Rapid, 87 040102.

March 2013: Invited session in APS March meeting 2013 in Baltimore on “Quantum Simulation with Photons” this year. Dimitris gave an invited talk and Changsuk, Changyoup, Amit and MingXia presented talks and posters on our recent works in this field. Check the program here

March 2013: Our work “Simulating neutrino oscillations in trapped ions” published at NJP 14 033028 (2012) has been selected for the “NJP Highlights of 2012” . When published last year, was covered in various science media: Phys.org “Dance like a neutrino: Quantum scheme to simulate neutrino oscillations “ , Science news line, SPACEDAILY, Eurekalert, Fermilab. Check out the TUC research highlight

February 2013. Our paper “Mimicking interacting relativistic theories with stationary pulses of light” has been published at PRL. See abstract further down on check the journal Phys. Rev. Lett. 110, 100502 (2013). Check out the Centre for Quantum Technologies research highlights

January 2013: A multi-group proposal comprised by several CQT groups including ourselves, was awared S$10 million for research into randomness!