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September 2018 “Discrete time crystal in globally driven interacting quantum systems without disorder”

Fig.1 (a) Schematic diagram showing the dynamics of the individual spins in our model for a small perturbation  in the spin flip. The presence of interaction helps to synchronize the spins.

Authors

W. C. Yu, J. Tangpanitanon, A. W. Glaetzle, D. Jaksch, D. G. Angelakis

Abstract

Time crystals in periodically driven systems have initially been studied assuming either the ability to quench the Hamiltonian between different many-body regimes, the presence of disorder or long-range interactions. Here we propose a scheme to observe discrete time crystal dynamics in a one-dimensional driven quantum system of the Ising type with short-range interactions and no disorder. The system is subject only to a periodic kick by a global magnetic field, and no extra Hamiltonian quenching is performed.

arXiv:1807.07738

Fig.1 (a) Schematic diagram showing the dynamics of the individual spins in our model for a small perturbation  in the spin flip. The presence of interaction helps to synchronize the spins.

Fig. 2(a) Color map of the Fourier spectrum of the stroboscopic magnetization in x direction with perturbation \epsilon as the driving parameter.

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Dec 2017-publication in Science: Spectroscopic signatures of localization with interacting photons in superconducting qubits (collaboration with Google-Martinis group)

The international team used photons in Google’s quantum chip to simulate the surprising and beautiful pattern of the ‘Hofstadter butterfly’, a fractal structure characterizing the behaviour of electrons in strong magnetic fields. The results, published 1 December in Science, show how quantum simulators are starting to live up to their promise as powerful tools,…
Read more from CQT highlight for non specialists  ” CQT researchers collaborate in quantum simulations on Google’s superconducting chip” and from USBC highlight ” Simulating physics “

 

This work is highlighted in 12 science news including Strait Time phys.orgeurekalertsciencedailytech2.orghousseniawritingtuc.gr , asian scientist, technology networks, nanowerk, alphagalileo, mgronline 

Science 358, 6367, pp. 1175-1179 (2017)

Authors

P. Roushan, C. Neill, J. Tangpanitanon, V.M. Bastidas, A. Megrant, R. Barends, Y. Chen, Z. Chen, B. Chiaro, A. Dunsworth, A. Fowler, B. Foxen, E. Je rey, J. Kelly, E. Lucero, J. Mutus, M. Neeley, C. Quintana, D. Sank, A. Vainsencher, J. Wenner, T. White, H. Neven, D. G. Angelakis, and J. Martinis

Abstracts

Quantized eigenenergies and their associated wave functions provide extensive information for predicting the physics of quantum many-body systems. Using a chain of nine superconducting qubits, we implement a technique for resolving the energy levels of interacting photons. We benchmark this method by capturing the main features of the intricate energy spectrum predicted for two-dimensional electrons in a magnetic field—the Hofstadter butterfly. We introduce disorder to study the statistics of the energy levels of the system as it undergoes the transition from a thermalized to a localized phase. Our work introduces a many-body spectroscopy technique to study quantum phases of matter.

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November 2017: Realizing topological relativistic dynamics with slow light polaritons at room temperature

Authors

M. Namazi, B. Jordaan, C. Noh, D. G. Angelakis, E. Figueroa

Abstract

Here we use a slow light quantum light-matter interface at room temperature to implement an analog simulator of complex relativistic and topological physics. We have realized the famous Jackiw-Rebbi model (JR), the celebrated first example where relativity meets topology. Our system is based upon interacting dark state polaritons (DSP’s) created by storing light in a rubidium vapor using a dual-tripod atomic system. The DSP’s temporal evolution emulates the physics of Dirac spinors and is engineered to follow the JR regime by using a linear magnetic field gradient. We also probe the obtained topologically protected zero-energy mode by analyzing the time correlations between the spinor components. Our implementation paves the way towards quantum simulation of more complex phenomena involving many quantum relativistic particles.

arxiv.org/1711.09346

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May 2017: Quantum Simulators with Photons and Polaritons: Merging Quantum Optics with Condensed Matter Physics

Check our book on “Quantum Simulators with Photons and Polaritons: Merging Quantum Optics with Condensed Matter Physics” by Springer!

This book reviews progress towards quantum simulators based on photonic and hybrid light-matter systems, covering theoretical proposals and recent experimental work.  Quantum simulators are specially designed quantum computers. Their main aim is to simulate and understand complex and inaccessible quantum many-body phenomena found or predicted in condensed matter physics, materials science and exotic quantum

See CQT highlight for non specialists.

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May 2017: A diagrammatic Diagrammatic Approach to Multiphoton Scattering

Authors

T.F. See, C. Noh, D.G. Angelakis, “A diagrammatic Diagrammatic Approach to Multiphoton Scattering”, Phys. Rev. A 95, 053845 (2017)

Abstract

We present a method to systematically study multiphoton transmission in one-dimensional systems comprised of correlated quantum emitters coupled to input and output waveguides. Within the Green’s function approach of the scattering matrix (S matrix), we develop a diagrammatic technique to analytically obtain the system’s scattering amplitudes while at the same time visualize all the possible absorption and emission processes. Our method helps to reduce the significant effort in finding the general response of a many-body bosonic system, particularly the nonlinear response embedded in the Green’s functions. We demonstrate our proposal through physically relevant examples involving scattering of multiphoton states from two-level emitters as well as from arrays of correlated Kerr nonlinear resonators in the Bose-Hubbard model.