# Matériaux et Phénomènes Quantiques

### Présentation

The laboratory « Matériaux et Phénomènes Quantiques » (Quantum Materials and Phenomena) is a joint research unit (UMR) of University Paris Diderot and CNRS. It involves about 120 people in total with a permanent staff of 51.

The laboratory specializes in the study of frontier quantum materials and in the development of novel quantum devices. These activities rely on a large spectrum of theoretical and experimental expertise in material physics, transport and optics, and technological platforms of clean-room fabrication, spectroscopy and high-resolution electronic microscopy.

The activities of the laboratory span:

- novel materials at the nanoscale: nanocrystals, functionalized nanotubes, multiferroics, 2D materials, etc.
- novel phases of matter: quantum fluids of light, ultrastrong coupling in cavity, unconventional superconductivity, strongly correlated systems, topological phases, etc.
- nano-optical systems: optomechanics, nonlinear nanophotonics, nanoplasmonics, etc.
- quantum engineering and quantum information: quantum optoelectronic devices, quantum photonic circuits, trapped ions, hybrid organic/inorganic devices, surface and interface engineering.

Current projects of the laboratory include the development of novel probes for the investigation of quantum materials, such as time-resolved Raman spectroscopy, optomechanical atomic force microscopy, and scanning tunneling microscopy under optical excitation. Reciprocally, frontier materials are being tested as building blocks to realize novel functionalities in optomechanical sensors, nonlinear and quantum photonics devices, or in cavity embedded transport experiments.

### [hal-04590307] Reconfigurable generation of spatial entanglement in nonlinear waveguide arrays

Date: 28 May 2024 - 12:19

Desc: Harnessing high-dimensional entangled states of light presents a frontier for advancing quantum information technologies, from fundamental tests of quantum mechanics to enhanced computation and communication protocols. In this context, the spatial degree of freedom stands out as particularly suited for on-chip integration. But while traditional demonstrations produce and manipulate path-entangled states sequentially with discrete optical elements, continuously-coupled nonlinear waveguide systems offer a promising alternative where photons can be generated and interfere along the entire propagation length, unveiling novel capabilities within a reduced footprint. Here we exploit this concept to implement a compact and reconfigurable source of spatially entangled photon pairs based on parametric down-conversion in AlGaAs nonlinear waveguides arrays. We use a double-pump configuration to engineer the output quantum state and implement various types of spatial correlations, exploiting a quantum interference effect between the biphoton state generated in each pumped waveguide. This demonstration, at room temperature and telecom wavelength, illustrates the potential of continuously-coupled systems as a promising alternative to discrete multi-component quantum circuits for leveraging the high-dimensional spatial degree of freedom of photons.

### [hal-04328946] Hybrid III-V/Silicon photonic circuits embedding generation and routing of entangled photon pairs

Date: 7 Dec 2023 - 12:23

Desc: The demand for integrated photonic chips combining the generation and manipulation of quantum states of light is steadily increasing, driven by the need for compact and scalable platforms for quantum information technologies. While photonic circuits with diverse functionalities are being developed in different single material platforms, it has become crucial to realize hybrid photonic circuits that harness the advantages of multiple materials while mitigating their respective weaknesses, resulting in enhanced capabilities. Here, we demonstrate a hybrid III-V/Silicon quantum photonic device combining the strong second-order nonlinearity and compliance with electrical pumping of the III-V semiconductor platform with the high maturity and CMOS compatibility of the silicon photonic platform. Our device embeds the spontaneous parametric down-conversion (SPDC) of photon pairs into an AlGaAs source and their subsequent routing to a silicon-on-insulator circuitry, within an evanescent coupling scheme managing both polarization states. This enables the on-chip generation of broadband telecom photons by type 0 and type 2 SPDC from the hybrid device, at room temperature and with internal pair generation rates exceeding $10^5$$s^{-1}$ for both types, while the pump beam is strongly rejected. Two-photon interference with 92% visibility (and up to 99% upon 5 nm spectral filtering) proves the high energy-time entanglement quality characterizing the produced quantum state, thereby enabling a wide range of quantum information applications on-chip, within an hybrid architecture merging the assets of two mature and highly complementary platforms in view of out-of-the-lab deployment of quantum technologies.

### [hal-02467226] Universality at work – the local sine-Gordon model, lattice fermions, and quantum circuits

Date: 4 Feb 2020 - 21:17

Desc: We review the intriguing many-body physics resulting out of the interplay of a single, local impurity and the two-particle interaction in a one-dimensional Fermi system. Even if the underlying homogeneous correlated system is taken to be metallic, this interplay leads to an emergent quantum phase transition between metallic and insulating states. We show that the zero temperature critical point and the universal low-energy physics associated to it, is realized in two different models, the field theoretical local sine-Gordon model and spinless fermions on a lattice with nearest-neighbor hopping and two-particle interaction, as well as in an experimental setup consisting of a highly tunable quantum circuit. Despite the different high-energy physics of the three systems the universal low-energy scaling curves of the conductance as a function of temperature agree up to a very high precision without any free parameter. Overall this provides a convincing example of how emergent universality in complex systems originating from a common underlying quantum critical point establishes a bridge between different fields of physics. In our case between field theory, quantum many-body theory of correlated Fermi systems, and experimental circuit quantum electrodynamics.

### [hal-03601442] Enhanced Cavity Optomechanics with Quantum-Well Exciton Polaritons

Date: 8 Mar 2022 - 11:38

Desc: Semiconductor microresonators embedding quantum wells can host tightly confined and mutually interacting excitonic, optical, and mechanical modes at once. We theoretically investigate the case where the system operates in the strong exciton-photon coupling regime, while the optical and excitonic resonances are parametrically modulated by the interaction with a mechanical mode. Owing to the large exciton-phonon coupling at play in semiconductors, we predict an enhancement of polariton-phonon interactions by 2 orders of magnitude with respect to mere optomechanical coupling: a near-unity single-polariton quantum cooperativity is within reach for current semiconductor resonator platforms. We further analyze how polariton nonlinearities affect dynamical backaction, modifying the capability to cool or amplify the mechanical motion.

### [hal-02415118] Degradation of ZnGa2O4:Cr3+ luminescent nanoparticles in lysosomal-like medium

Date: 16 Dec 2019 - 22:15

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### Autres contacts

Université Paris Diderot - Paris 7

U.F.R. Physique

Bâtiment Condorcet

10, rue Alice Domon et Léonie Duquet

75205 PARIS CEDEX 13