**Non-ergodic properties, in particular localization, multifractality and absence or anomalous thermalization properties, in quantum disordered or chaotic systems. **

*(Gabriel LEMARIE)*

From Phys. Rev. B 106, 214202 (2022). Illustration of the disorder driven Anderson localization transition on random graphs of effective infinite dimensionality.

Recently, we have addressed [García-Mata (2022)] the Anderson transition in random graphs, which is a phenomenon of interest because it may help us better understand the many-body localization (MBL) transition. We have considered an Anderson model on a swall-world model, a type of network where nodes are connected not only to their immediate neighbors but also to nodes that are farther away, resulting in short path lengths between nodes and effective infinite dimensionality. While the existence and value of a critical disorder separating a localized and delocalized phase in random graphs are well established, the nature of the transition is not well understood. Recent work on the MBL transition predicts that the flow is of Kosterlitz-Thouless type, and this paper shows that the Anderson transition on graphs displays the same type of flow. ** **

*Nicolas Laflorencie, Gabriel Lemarié, Nicolas Macé*

Topological order in random interacting Ising-Majorana chains stabilized by many-body localization

Rev. Research 4, L032016 (2022)*C. W. Foo, N. Swain, P. Sengupta, G. Lemarié, S. Adam*

A stabilization mechanism for many-body localization in two dimensions

arXiv:2202.09072*Sen Mu, Nicolas Macé, Jiangbin Gong, Christian Miniatura, Gabriel Lemarié, Mathias Albert*

Superfluidity vs prethermalisation in a nonlinear Floquet system

EPL 140 50001 (2022)*Ignacio García-Mata, John Martin, Olivier Giraud, Bertrand Georgeot, Rémy Dubertrand, Gabriel Lemarié*

Critical properties of the Anderson transition in random graphs: two-parameter scaling theory, Kosterlitz-Thouless type flow and many-body localization

Rev. B 106, 214202 (2022)*Maxime Martinez, Gabriel Lemarié, Bertrand Georgeot, Christian Miniatura, Olivier Giraud*

Coherent forward scattering as a robust probe of multifractality in critical disordered media

arXiv:2210.04796*Ankita Chakrabarti, Cyril Martins, Nicolas Laflorencie, Bertrand Georgeot, Éric Brunet, Gabriel Lemarié*

Traveling/non-traveling phase transition and non-ergodic properties in the random transverse-field Ising model on the Cayley tree

arXiv:2212.13593

** **

**Using ultracold gases for quantum simulation of condensed-matter or/and high-energy physics**

*(David WILKOWSKI)*

We perform quantum simulations mimicking Hamiltonians with an artificial gauge field. Recently, we studied the matter-wave dynamic in a non-Abelian gauge field and found an oscillatory behaviour (Figure a and b) that it is governed by a non-inertial force leading to spin-Hall effect associated to the spin-texture of the system (Figure c). This dynamics is a generalization of the Zitterbewegung relativistic effect in a two-dimensional non-Abelian gauge field.** **

** **

*Li, K. Lim, S. Das, T. Zanon-Willette, C.-H. Feng, P. Robert, A. Bertoldi, P. Bouyer, C. C. Kwong, S.-Y. Lan, and D. Wilkowski, Bi-color atomic beam slower and magnetic field compensation for ultracold gases, AVS Quantum Science***4**, 046801 (2022).*E. Ballantine, D. Wilkowski, J. Ruostekoski, Optical magnetism and wavefront control by arrays of strontium atoms, Phys. Rev. R***4**, 033242 (2022).*S. Madasu, M. Hasan, K. D. Rathod, C. C. Kwong, D. Wilkowski, Datta-Das transistor for atomtronic circuits using artificial gauge fields, Phys. Rev. R***4**, 033180 (2022).*Hasan, C. S. Madasu, K. D. Rathod, C. C. Kwong, D. Wilkowski, Evolution of an ultracold gas in a non-Abelian gauge fields: Finite temperature effect, Q. Elec***52**, 532 (2022).*Zanon-Willette, D. Wilkowski, R. Lefevre, A. V. Taichenachev, V. I. Yudin, Generalized hyper-Ramsey-Bordé matter-wave interferometry: Quantum engineering of robust atomic sensors with composite pulsesPhys. Rev. R,***4**, 023222 (2022).*Zanon-Willette, D. Wilkowski, R. Lefevre, A. V. Taichenachev, V. I. Yudin, SU(2) hyper-clocks: Quantum engineering of spinor interferences for time and frequency metrologyPhys. Rev. R,***4**, 023117 (2022).*Mehedi Hasan, Chetan Sriram Madasu, Ketan D. Rathod, Chang Chi Kwong, Christian Miniatura, Frederic Chevy, David Wilkowski, Wave-packet Dynamics in Synthetic Non-Abelian Gauge Fields, Phys. Rev. Lett.,***129**, 130402 (2022).**Editor’s suggestion, featured in physics**.*Chetan Sriram Madasu, Chang Chi Kwong, David Wilkowski, Kanhaiya Pandey, Homodyne detection of a two-photon resonance assisted by cooperative emission, Phys. Rev. A***105**, 013713 (2022).*Chung Chuan Hsu, Remy Larue, Chang Chi Kwong, and David Wilkowski, Laser-induced thermal source for cold atoms, Scientific report***12**, 868 (2022).

Figure: (a) Oscillation of an atomic wave-packet in a non-Abelian gauge field. (b) Discrete velocity distribution, obtained after time of flight, which indicates the quantum nature of the phenomenon. (c) Spin texture responsible for spin-Hall effect. Figures extracted from Phys. Rev. Lett., 129, 130402 (2022)

**Using neural networks and quantum simulators to describe quantum matter **

*(Dario POLETTI)*

Figure: (a) Depiction of a spin boson model for two spins. The two spin sites are coupled to one harmonic oscillator of frequency ω via coupling parameter λ. Each of the spins dissipates independently into the environment at a rate of γ. Figure taken from Entropy, 24(12), 1766 (2022)

We analyze many-body quantum system by representing them with an ansatz formed by a neural network. Within this framework, we use variational quantum Monte Carlo to find the ground state. We have been working on methods to render more efficient and effective the search of the ground state. In particular we have proposed and tested the use of transfer learning, for which the parameters of a network at a certain scale are initialized from the parameters learned at smaller scales. More recently we have also proposed the sequential local optimization algorithm, which can help improve the optimization of the neural network parameters, and approach an accurate description of the ground state.

We also explore, in parallel the simulation of interacting quantum systems with near term quantum computers.

*V. Balachandran, D. Poletti, “Relaxation Exponents of OTOCs and Overlap with Local Hamiltonians”, Entropy 25(1), 59 (2023)**A. Burger, L.C. Kwek, D. Poletti, “Digital Quantum Simulation of the Spin-Boson Model under Markovian Open-System Dynamics”, Entropy, 24(12), 1766 (2022)**J. Qi, X. Xu, D. Poletti, HK Ng, “Efficacy of noisy dynamical decoupling”, arXiv:2209.09039 (2022)**R. Erbanni, K. Bharti, L.C. Kwek, D. Poletti, “NISQ algorithm for the matrix elements of a generic observable”, arXiv:2205.10058 (2022)*

**Studying quantum transport and thermalization/condensation for matter waves subjected to random potentials, interactions or artificial gauge fields**

*(Christian MINIATURA)*

We have studied the momentum-space signatures of the Anderson metal-insulator transition in 2D disordered spin-orbit systems (Fig.1). The critical exponent and mobility edge of the metal-insulator transition have been successfully obtained through a finite-time analysis of the coherent backscattering (anti)-peak width (Fig.2). An anomalous residual diffusion has been also identified at the mobility edge. A spin localization phenomenon has been also observed in the deep localized regime [arXiv:2301.07288v1 (2023)].

** **

*Prethermalization and wave condensation in a nonlinear disordered Floquet system**P. Haldar, S. Mu, B. Georgeot, J. Gong, C. Miniatura, and G. Lemarié**Submitted to Phys. Rev. Res. Lett. (2022)**arXiv:2109.14347v1 (2021)**Momentum signatures of site percolation in disordered two-dimensional ferromagnets**D. Tay, B. Grémaud, and C. Miniatura**Phys. Rev. B 106, 014203 (2022)**Time Reversal and Reciprocity**O. Sigwarth and C. Miniatura**AAPPS Bull. 32, 23 (2022)**Wave Packet Dynamics in Synthetic Non-Abelian Gauge Fields**M. Hasan, C. S. Madasu, K. D. Rathod, C. C. Kwong, C. Miniatura, F. Chevy, and D. Wilkowski**Phys. Rev. Lett. 129, 130402 (2022)**Superfluidity vs thermalisation in a nonlinear Floquet system**S. Mu, N. Macé, J. Gong, C. Miniatura, G. Lemarié, and M. Albert**Europhy. Lett. 140, 50001 (2022)**Coherent forward scattering as a robust probe of multifractality in critical disordered media**M. Martinez, G. Lemarié, B. Georgeot, C. Miniatura, and O. Giraud**Accepted for Publication in SciPost (2022)**arXiv:2210.04796v1 [cond-mat.dis-nn] (2022)**Momentum-space signatures of the Anderson transition in a symplectic, two-dimensional, disordered ultracold gas**E. Arabahmadi, D. Schumayer, B. Grémaud, C. Miniatura, and D. A. W. Hutchinson**Submitted to Phys. Rev. Lett. (2023)**arXiv:2301.07288v1 [cond-mat.dis-nn] (2023)*

Figure 1:Momentum distribution obtained for an initial plane wave state with spin up. A CFS peak (red) is observed in the parallel spin scattering channel while a CBS anti-peak (blue) is observed in the opposite spin scattering channel.

Figure 2:Scaling function numerically extracted from the time dependence of the CBS anti-peak width. The horizontal dashed line marks the mobility edge (W* ≈ 5.9) and the algebraic behaviour near the tip gives the critical exponent of the transition (𝜈 ≈ 2.73).

**Atomtronics & Integrated Photonic Chips**

Figure 1: Three-terminal Aharonov-Bohm circuit with source lead (left) attached to a ring with two drain leads (right).

Figure 2: Applications of three-terminal cold atom Aharonov

Figure 3: Quantum autoencoder and its training strategies

Figure 4: The packaging of the silicon photonic chip wire-bonded to a PCB.

**Atomtronics**

- We study three-terminal ring circuit pierced by a synthetic magnetic flux.
- The flux controls the atomic current through the ring via the Aharonov-Bohm effect.
- Flux-induced transition of reflections from an Andreev-like negative density to positive density.is demonstrated.
- By changing the flux linearly in time, we convert constant matter wave currents into an AC modulated current.

**Integrated Photonic Chips**

- Quantum autoencoders serve as efficient means for quantum data compression.
- We demonstrate the use of autoencoder to reduce resource costs for quantum teleportation in high-dimensional
- Unsupervised machine learning is applied to train the on-chip autoencoder, enabling the compression and teleportation of any state from a high-dimensional subspace

*Burger, A., Kwek, L. C.~, & Poletti, D~ (2022). Digital quantum simulation of the spin-boson model under Markovian open-system dynamics..Entropy, 24 (12), 1766, 2.642.**Zhang, H., Lau, J.W.Z, Wan, L., Shi, L., Shi, Y., Cai, H, Luo, X., Lo, G.Q., Lee, C.K., Kwek, L.C., & Liu, A.Q. (2022). Molecular Property Prediction with Photonic Chip-Based Machine Learning. Laser & Photonics Reviews , 202200698, 13.14**Amico, L., Anderson, D., Boshier, M., Brantut, J-P, Kwek, L.C., Minguzzi, A & von Klitzing,W. (2022). Atomtronic circuits: From many-body physics to quantum technologies. Reviews of Modern Physics , 94 (4), 041001, 54.494.**Koor, K., Bomantara, R.W. & Kwek, L.C. (2022). Symmetry-protected topological cornermodes in a periodically driven interacting spin lattice. Physical Review B , 106 (19),195122, 3.908.**Hui Zhang, Lingxiao Wan, Tobias Haug, Wai-Keong Mok, Stefano Paesani, Yu-zhi Shi, Hong Cai, Lip Ket Chin, Muhammad Faeyz Karim, Limin Xiao, Xianshu Luo, Feng Gao, Bin Dong, Syed Assad, MS Kim, Anthony Laing, Kwek L.C., & Ai Qun Liu (2022). Resource-efficient high-dimensional subspace teleportation with a quantum autoencoder. Science Advances , 8(40), eabn9783, Impact factor: 14.14.**Kishor Bharti, Maharshi Ray, Zhen-Peng Xu, Masahito Hayashi, Kwek L.C., & Adán Cabello (2022). Graph-Theoretic Approach for Self-Testing in Bell Scenar-ios. PRX Quantum, 3(3), 030344.**Yuan Li, Lingxiao Wan, Hui Zhang, Huihui Zhu, Yuzhi Shi, Lip Ket Chin, Xiaoqi Zhou, Kwek L.C., & Ai Qun Liu (2022). Quantum Fredkin and Toffoli gates on a versatile programmable silicon photonic chip. npj Quantum Information , 8(1), 1-7, Impact Factor 7.385.**Bharti K., Haug T., Vedral V., & Kwek L.C. (2022). Noisy intermediate-scale quantum algorithm for semidefinite programming. Physical Review A , 105(5), 052445, Impact Factor 3.14.**Lau J.W.Z., Haug T., Kwek L.C.~, & Bharti K. (2022). NISQ Algorithm for Hamil-tonian simulation via truncated Taylor series. SciPost Physics, 12, 122.**Wen‐Qiang Liu, Hai‐Rui Wei,& Kwek L.C. (2022). Universal Quantum Multi‐Qubit Entangling Gates with Auxiliary Spaces. Advanced Quantum Technologies, 5(5), 2100136, Impact Factor: 5.31.**Guijiao Du, Chengcheng Zhou,& Kwek L.C. (2022). Compression and reduction of N ∗ 1 states by unitary matrices. Quantum Information Processing, 21(2), 1-11, Impact Factor 2.349.**HH Zhu, J Zou, H Zhang, YZ Shi, SB Luo, N Wang, H Cai, LX Wan, B Wang, XD Jiang, J Thompson, XS Luo, XH Zhou, LM Xiao, W Huang, L Patrick, M Gu, Kwek L.C., & AQ Liu (2022). Space-efficient optical computing with an integrated chip diffractive neural network. Nature Communications, 13(1), 1-9, Impact Fac-tor 12.124**Kishor Bharti, Alba Cervera-Lierta, Thi Ha Kyaw, Tobias Haug, Sumner Alperin-Lea, Abhinav Anand, Matthias Degroote, Hermanni Heimonen, Jakob S Kott-mann, Tim Menke, Wai-Keong Mok, Sukin Sim, Kwek L.C. , & Alan Aspuru-Guzik (2022). Noisy intermediate-scale quantum algorithms. Reviews of Modern Physics , 94(1), 015004, Impact Factor 54.494.**Lee, Chee Kong; Lau, Jonathan; Shi, Liang, & Kwek, L.C. (2022). Simulating Energy Transfer in Molecular Systems with Digital Quantum Computers. Journal of Chemical Theory and Computation , 18(3), 1347–1358, Impact Factor 6.8.**VM Bastidas, T Haug, C Gravel, L-C Kwek, WJ Munro, & Kae Nemoto (2022). Stroboscopic Hamiltonian engineering in the low-frequency regime with a one-dimensional quantum processor. Physics Review B , 105(7), 075140, Impact Factor 4.036.**Lau, J.W.Z., Lim, K.H., Shrotriya, H., & Kwek, L.C. (2022). NISQ computing: where arewe and where do we go?.AAPPS Bulletin, 32 (1), 1-30.**W.K. Mok, & Kwek L.C. (2022). Quantum Switchboard with Coupled-Cavity Ar-ray. Entropy, 24(1), 136, Impact Factor 2.419.**Wayne Jordan Chetcuti, Tobias Haug, Kwek L.C., & Luigi Amico (2022). Persis-tent current of SU (N) fermions. SciPost Physics , 12(1), 033, 6.45.*