Dimitris Angelakis is a tenured Associate Professor at School of Electronic and Computer Engineering, Technical University of Crete and jointly a Principal Investigator at Centre for Quantum Technologies, Singapore leading the Quantum Optics and Quantum Simulators Group. He was born and raised in Chania, Crete in 1975. 1993-1998 he did his BSc and MSc studies in Physics University of Crete. 1998-2001 was a PhD student at Imperial College, QOLS group supported by Greek State Scholarship Foundation. He was elected junior research fellow at University of Cambridge (St Catharine's JRF) and worked at DAMTP and the Centre for Quantum Computation in Cambridge 2001 to end of 2007. In 2008, he took over a faculty appointment at the Science Department Technical University of Crete, and in 2013 he moved to the School of Electronic and Computer Engineering. Since 2010 he is also a Principal Investigator at the Centre for Quantum Technologies, Singapore. His background is in theoretical quantum physics and quantum optics. His research interest are in quantum optical implementations of quantum computation and quantum simulation, quantum many-body physics and quantum technologies. He quite enjoys discussing science at all levels, sampling good wine and tries to learn play the Cretan Lyra. He is married with three children.Quantum Simulators and Quantum Technologies: Classical computers require enormous computing power and memory to simulate even the most modest quantum systems. That makes it difficult to model, for example, why certain materials are insulators and others are conductors or even superconductors. R. Feynman had grasped this since the 1980s and suggested to use instead another more controllable and perhaps artificial quantum system as a "quantum computer" or specifically in this case a "quantum simulator". Working examples of quantum simulator technologies today include extremely cold atoms trapped with lasers and magnetic fields and ions in electromagnetic traps. Photons and polaritons in light-matter systems have also recently emerged as a promising avenue and we are happy to be one of the leading groups in this area. With photons, exotic phenomena thought to exist only in strongly interacting electronic systems, such as Mott transitions, Fractional Hall effect, spin-charge separation, interacting relativistic theories and topological physics can be reproduced and understood in more detail. In addition to the "many-body stuff", he is also interested in the "few body" quantum effects found in nano-structures and cold ions systems interfaced with light. These hybrid systems are extremely interesting for the study of quantum effects like quantum interference and entanglement and for their potential use in building quantum memories and quantum processors. My work is mainly theoretical but we keep close contact with various experimental groups. --Open Positions at CQT the Postdoc and PhD levels in Quantum Optics and Quantum Simulation. Please contact at dimitris.angelakis-at-gmail.com--For candidates interested at postdoc positions at our Crete based operation, a recent call for proposals funded from the Greek Government is advertised here. --Our recent review article on "Quantum Simulations and Many-Body Physics with Light", Reports in Progress in Physics 80, 016401 (2016), arXiv:1604.04433 ---Check our book on "Quantum Simulators with Photons and Polaritons: Merging Quantum Optics with Condensed Matter Physics" by Springer!
Research in my group focuses among others on developing novel methods to describe and understand the quantum interactions between light and matter. Our research could be applied towards developing exotic quantum technologies devices such as single-photon switches, quantum processors and also for fundamental science in the area of strongly correlated quantum systems. Our work is highly interdisciplinary and spans areas such as quantum optics, nano-photonics, condensed matter physics, as well as quantum information science. Some of our activities are carried out in close collaboration with leading experimental groups in Europe, US and Asia. In more detail, the last few years we have been focusing in the area of quantum simulations of quantum many body effects with strongly-coupled light-matter set ups using photons and polaritons. A number of experimental platforms, such as cold Rydberg gases or cold atoms coupled to nano-photonic structures, as well as circuit QED now make it possible to robustly observe strong coupling and nonlinear optical interactions at the quantum level. Our group investigates methods to control and utilize these nonlinear interactions, in order to produce exotic states of light useful for quantum computation and quantum simulation. We develop novel theoretical techniques to solve the challenging problem of the dynamics of strongly interacting photons and polaritons and apply them to specific platforms ranging from slow-light set ups, to superconducting QED resonator arrays and integrated photonic chips. Our methods are based upon a combination of principles from quantum optics, condensed matter physics, and quantum field theory including both analytical and sophisticated numerical methods.1. Dimitris G. Angelakis, Marcelo F. Santos, Sougato Bose, “Photon blockade induced Mott transitions and XY spin models in coupled cavity arrays”, Phys. Rev. A (Rap. Com.) vol. 76, 031805 (2007)(arXiv:quant-ph/0606159). 450 citations Highlighted in the cover of New Scientist Jan. 2007
4. Dimitris G.
Angelakis, Alastair Kay, “Weaving light-matter qubits into a one way
quantum computer”, New J. Phys. Vol. 10, 023012 (2008). selected
by Sciencewatch.com as one of the top 20 papers with most citations in the years 2008 and 2009 in the field of quantum computing.
Highlighted at Phys,org 6. D. G. Angelakis, M. Huo, E. Kyoseva, LC Kwek, “Luttinger liquid photons and spin-charge separation in hollow-core fibers'. Phys. Rev. Lett. 106, 153601 (2011). 40 citations, Highlighted as an "Editors Suggestion", as a Viewpoint article in Physics and also as Research Highlight in Nature: Nature, 472, 262 (2011)
Group news highlights:
December 2016: Our joint work with Berlin in "Driven open quantum systems and Floquet stroboscopic dynamics November 2016: Check out the October 2016: September 2016: Our joint work with Berlin in "Semiclassical bifurcations and topological phase transitions in a one-dimensional lattice of coupled Lipkin-Meshkov-Glick models" has been published in Phys. Rev. E 94, 032123 (2016) August 2016: Kishor Bharti joined the group as a PhD student. Welcome to the team Kishor! July 2016: We show how to implement topological or Thouless pumping of interacting photons in one dimensional nonlinear resonator arrays, by simply modulating the frequency of the resonators periodically in space and time. The interplay between interactions and the adiabatic modulations enables robust transport of Fock states with few photons per site. We analyze the transport mechanism via an effective analytic model and study its topological properties and its protection to noise. We conclude by a detailed study of an implementation with existing circuit QED architectures June 2016:
In this review we discuss the works in the area of quantum simulation and many-body physics with light, from the early proposals on equilibrium models to the more recent works in driven dissipative platforms.. We review the major theory results and also briefly outline recent developments in ongoing experimental efforts involving different platforms in circuit QED, photonic crystals and nanophotonic fibers interfaced with cold atoms. January 2016: Victor Bastidas joined the group as a postdoc. Welcome to the team Victor! December 2015: Dimitris inivted talk in KITP, UCSB entitled "Engineering and probing many-body states of light in driven-dissipative cavity arrays" can be found here (slides and video) November 2015: Our work on "Few Photon Transport in Many-Body Photonic Systems: A Scattering Approach" is published in Phys. Rev A. With the help of two-photon scattering matrix of in- and out-states, we find that the use of quantum input states in photonic quantum simulators such as those implemented in coupled cavity arrays, allows one to observe not only stronger spectroscopic signals of the underlying strongly correlated states but also a faithful representation of their intensity-intensity correlations, as compared to the conventional classical driving fields. Our analysis can be applied for many-body spectroscopy of any many-body model amenable to a photonic quantum simulation, including the Jaynes-Cummings-Hubbard, the extended Bose-Hubbard, and a whole range of spin models. October 2015: Dimitris, Jirawat and Ting Feng will be participating at the exciting KITP program for "Many-body physics with light" until December 18th! Dimitris will be delivering a talk on Wednesday 25/11 on "Engineering and probing many-body states of light in driven dissipative arrays". September 2015: Changyoup and Changsuk are leaving the group after few excellent years with us moving to jobs in Germany and Korea All the best guys, was great to have you on board!
Read the relevant highlight written for non-specialists here! March 2014: "Many-body physics with light", will be the theme of one of the prestigious Kavli Institute of Theoretical Physics (KITP) three months programes in 2015! Dimitris is one of the invited participants.
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.
## MPNS COST Action MP1403Nanoscale Quantum OpticsThe 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.
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.
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.
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 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!
July 2012: Our invited paper on "Spinons and hollons with polarized photons in a nonlinear waveguide" was published in the FOCUS ON BOSE CONDENSATION PHENOMENA IN ATOMIC AND SOLID STATE PHYSICSMay 2011: Interview and article in Greek national newspaper “TO BHMA” by Tasos Kafantaris, Science section, Sunday 8 May 2011 "Liquid photons: A la Grec" (in Greek). April 2011: Research Highlight in Nature: "Optical Physics: A liquid of photons", Nature, 472, 262 (2011) related to our work on spin charge separation with light. March 2011: Publication
“Luttinger liquid of photons and spin-charge separation in hollow-core fibers PRL 2011” was selected as an "Editors Suggestion" by Physical Review
Letters and was the theme of a Viewpoint
article in Physics entitled “In a tight spot spin and charge
separate” in Physics 4. 30 20111 by G. A
FIete January 2012: Priyam joins the group, welcome Priyam! Highlights of recently completed works(under construction):
We introduce a scheme for generating entanglement between two quantum dots using a plasmonic waveguide made from an array of metal nanoparticles. We show that the scheme is robust to loss, enabling it to work over long distance plasmonic nanoparticle arrays, as well as in the presence of other imperfections such as the detuning of the energy levels of the quantum dots. Here, the entanglement is generated by using dipole-induced interference effects and detection-based postselection. Thus, contrary to the widely held view that loss is major problem for quantum plasmonic systems, we provide a robust-to-loss entanglement generation scheme that could be used as a versatile building block for quantum state engineering and control at the nanoscale
We introduce the term Majoranon to describe particles that obey the Majorana equation, which are different from the Majorana fermions widely studied in various physical systems. A general procedure to simulate the corresponding Majoranon dynamics, based on a decomposition of the Majorana equation into two Dirac equations, is described in detail. It allows the simulation of the two-component chiral spinors, the building blocks of modern gauge theories, in the laboratory with current technology. Specifically, a Majoranon in one spatial dimension can be simulated with a single qubit plus a continuous degree of freedom, for example a single trapped ion. Interestingly, the dynamics of a Majoranon deviates most clearly from that of a Dirac particle in the rest frame, in which the continuous variable is redundant, making a possible laboratory implementation feasible with existing set ups.
One of the most well known relativistic field theory models is the Thirring model (TM). Its realization candemonstrate the famous prediction for the renormalization of mass due to interactions. However, experimental verification of the latter requires complex accelerator experiments whereas analytical solutions of the model can be extremely cumbersome to obtain. In this work, following Feynman's original proposal, we propose a alternative quantum system as a simulatorof the TM dynamics. Here the relativistic particles are mimicked, counter-intuitively, by polarized photons in a quantum nonlinear medium. We show that the entire set of regimes of the Thirring model -- bosonic or fermionic, and massless or massive -- can be faithfully reproduced using coherent light trapping techniques. The sought after correlations' scalings can be extracted by simple probing of the coherence functions of the light using standard optical techniques.
the shape and depth of the underlying potential on demand. We conclude by proposing how one of the signature effects of nonlinear dynamics, bistablity, can be experimentally observed in our set up using current or near future technology.
Dynamics of quantum light in integrated nonlinear waveguide arrays and generation of robust continuous variable entanglement. (Preprint at http://arxiv.org/abs/1201.4303) has been accepted in Phys. Rev. A
We study a class of nonlinear waveguide arrays where the waveguides are endowed with quadratic non- linearity and are coupled through the evanescent overlap of the guided modes. We study both the stimulated and spontaneous process in the array and show the viability of such an array as a platform for generating both bipartite and tripartite continuous variable entanglement on demand. We explicitly address the affect of realistic losses on the entanglement produced, briefly discuss the possible types of nonlinear materials that could be used, and suggest solutions to the possible phase matching issues in the waveguides. The simultaneous generation and manipulation of the light on a single waveguide chip circumvents the usual bandwidth problems associated with the use of external bulky optical elements and makes this avenue promising for further investigation.
News July 2011: Neutrino oscillations in trapped ions, arXiv:1106.4936We propose a scheme to simulate neutrino oscillations which is experimentally implementable with existing techniques for neutrinos in 1+1 dimensions. We demonstrate how the three generation neutrino oscillations is realizable with three trapped ions. In 1+1 dimensions only experimentally proven interactions are required. The same method can be applied to two generation neutrino oscillations, which require less resources. News June 2011: Probing the BCS-BEC crossover with photons in a nonlinear optical fiber, arXiv:1106.4936We propose a scheme where strongly correlated photons generated inside a hollow one dimensional waveguide filled with two cold atomic species can be used to simulate the BCS-BEC crossover. We first show how stationary light-matter excitations (polaritons) in the system can realize an optically tunable two component Bose-Hubbard model, and then analyze the optical parameters regime necessary to generate an effective Fermi-Hubbard model of photons exhibiting Cooper pairing. The characteristic correlated phases of the system can be efficiently observed due to the {\it in situ} accessibility of the photon correlations with standard optical technology.
It has also beed selected as an "Editors Suggestion" and Viewpoint article on our work by G. A Fiete that has appeared in Nature Research Highlight: "Optical Physics: A liquid of photons", Nature, 472, 262 (2011) Sunday 8.5.2011 Coverage of the above work by the Greek Sunday newspaper Vima Science (in Greek) One of the most counterintuitive characteristics of one dimensional electron gases is spin-charge separation.In this case the electrons cease to behave as single particles comprised of spin and charge. Instead collective excitations appear carrying only charge (and no spin) or only spin (and no charge). Important efforts trying to measure the spectral function and observe distinct spinon and holon branches in condensed matter systems have been inconclusive so far due to the complexity of the structures involved. We show here that spin-charge separation could be efficiently observed in strongly correlated quantum optical system. Quasi-particles formed from light-matter excitations (polaritons) trapped in a waveguide, are shown to obey the Lieb Liniger dynamics of a two component quantum liquid. We explain how to prepare and drive the photonic system to a strongly interacting regime and then proceed by explaining how to measure the corresponding effective spin/charge densities and velocities through standard optical methods. (Left) A schematic of system under consideration (Right) The single particle spectral function showing distinct effective spin and charge brances propagating with different velocities! News 24.3.2011: Our new work on how to "pin photons into order" is completed, here is a preprint ## Pinning quantum phase transition of photons in a hollow-core fiber (arXiv:1103.4856v1)Many-body quantum phenomena are responsible for fascinating physics like superconductivity and quantum phase transitions.One-dimensional (1D) systems of interacting particles are particularly interesting as the combined effects of interactions and quantum fluctuations lead to radically different behavior from what expected in more dimensions. One of the significant most famous example is the pinning of strongly interacting particles in an orderly line even in the absence of any lattice potential. Motivated by recent success in generating strong nonlinear interactions between trapped photons in optical waveguides, we analyze how a pinning transition for photons in a hollow-core fiber could be observed. Our optical proposal, except being counterintuitive as photons as used to describe massive particles, allows for the efficient detection of the resulting many body states through standard photon correlations measurements. (Right) The phase diagram of the realizable correlated photonic states as a function of the external optical parameters.We assume a total atomic decay rate from the upper level around 20MhZ, approximately $10^{5}$ atoms into a few cm fiber and the input quantum light pulse containing roughly 10 photons. |