Many-Body Entanglement in Solid-State Emitters

Abstract

The preparation and control of quantum states lie at the heart of quantum information science (QIS). Recent advances in solid-state quantum emitters (QEs) and nanophotonics have transformed the landscape of quantum photonic technologies, enabling scalable generation of quantum states of light and matter. A new frontier in solid-state quantum photonics is the engineering of many-body interactions between QEs and photons to achieve robust coherence and controllable many-body entanglement. These entangled states, including photonic graph and cluster states, superradiant emission, and emergent quantum phases, are promising for quantum computation, sensing, and simulation. However, intrinsic inhomogeneities and decoherence in solid-state platforms pose significant challenges to realize such complex entangled states. This review provides an overview of the fundamental many-body interactions and dynamics at the light-matter interfaces of solid-state QEs, and discusses recent advances in mitigating decoherence and harnessing robust many-body coherence.

Figures (7)

• Figure 1: Overview of achieving many-body entanglement with solid-state quantum emitters integrated in nanophotonics. Top: Representative platforms, including vacancies in wide-bandgap crystals, epitaxial quantum dots, molecules, hBN defects, 2D excitons, and Rydberg excitons, highlighting complementary strengths in coherence, scalability, and intrinsic nonlinearity. Quantum dot image reproduced with permission from Ref. gurioli_droplet_2019, and image of 2D exciton reproduced with permission from Ref. li_proximity-induced_2023. Center: Photonic interfaces enhance light–matter coupling and mediate long-range emitter–emitter interactions through coupling to shared modes. Bottom: Nanophotonic systems, including photonic crystal cavities and waveguides, plasmonic structures, hybrid devices, and inverse design, enable programmable photon-mediated couplings. Right: These capabilities yield quantum-optical resources (superradiance, multi-photon cluster/graph states, and quantum phase transitions) and enable interacting many-body states.
• Figure 2: Many-body entanglement and collective emission in solid state QE systems. (a) Spectra of the superradiant ($|+\rangle$) and subradiant ($|-\rangle$) single-excitation states of two sub-wavelength spaced organic molecules, showing an extinguishing of the subradiant linewidth as the molecules are tuned into resonance. (b) Fluorescence spectrum of the system in a), displaying an additional two-photon peak at sufficiently large excitation power associated with the fully-excited two-emitter state. (c) Ratio of the heights of super- and subradiant peaks in a) for varied detuning. d) Photon correlation functions for the states $|\pm\rangle$ in a), displaying modified Rabi frequencies and lifetimes. Panels a - d are adapted with permission from lange2024superradiant. (e) Theoretical prediction of many-body superradiance in two-dimensional sub-wavelength QE arrays. The emergence of a superradiant burst for inter-atomic spacings below a critical value is found to be robust against positional disorder (reproduced with permission from masson2022universality). (f) Electron micrograph of a three-dimensional perovskite quantum-dot superlattice and (g) photon correlation function $g^{(2)}(\tau)$ showing photon bunching at zero delay as a signature of superradiance in this system (panels f - g are adapted with permission from raino_superfluorescence_2018). (h) Moiré excitons in a $WSe_2$/$WS_2$ bilayer mapped to an extended Bose–Hubbard model with strong on-site exciton–exciton interaction $U_{ex}$ and long-range dipolar coupling $V_{DD}$. Schematic potential (i) and time-resolved transport (j) reveal a crossover to a correlated (Mott-insulating) phase at high filling $V_{ex} \gtrsim 1$, evidenced by a suppressed mean-squared displacement and a turning point in the dynamics. Panels h - j are reproduced with permission from Ref. Deng2025.
• Figure 3: Collective interactions of multiple solid-state quantum emitters in nanophotonic environments observed across molecular, quantum-dot, and color-center platforms. (a) Schematic cavity transmission spectra and energy-level diagrams illustrating three regimes: (i) two emitters off resonance with each other but near-resonant with the cavity, decaying independently, (ii) emitters resonant with each other and with the cavity (dissipative regime), where superradiant and subradiant collective states form, and (iii) emitters resonant with each other but detuned from the cavity (dispersive regime), where coherent dipole–dipole interactions split the symmetric and antisymmetric states. (b) Cavity-mediated interaction of two silicon-vacancy (SiV$\space^-$) centers in a diamond nanocavity, showing formation of bright (superradiant, |S⟩) and dark (subradiant, |D⟩) collective states, reproduced with permission from Ref. evans2018photon. (c) Superradiant emission observed from two V$_{si}$ centers in a thin-film SiC microdisk cavity manifested through bunching in photon correlation measurements, reproduced with permission from Ref. lukin2023two. (d) Observation of super- and subradiant emission from pairs of quantum dots deterministically positioned in a nanophotonic waveguide, mediated by long-range radiative coupling, reproduced with permission from Ref. tiranov2023collective. (e) Two dibenzoterrylene (DBT) molecules coupled to a 1D photonic crystal cavity, interacting either dissipatively via the cavity mode or dispersively through dipole–dipole coupling, reproduced with permission from Ref. lange2025cavity. (f) Long-range dipole-dipole interactions mediated by plasmonic nanoparticle lattice manifested through decay lifetime at various acceptor concentrations, reproduced with permission from Ref. boddeti2022dipole-dipole.
• Figure 4: Pathways to achieve strong photon nonlinearity through exciton polaritons. (a) Excitation and re-emission of an exciton polariton by a single photon. Interactions shift the mode off resonance, suppressing multi-photon transmission (polariton blockade), reproduced with permission from Ref. gerace2019quantum (b) Detuning dependent coincidence counts and the corresponding nonclassical correlations from polaritons based on quantum well microcavity, reproduced with permission from Ref delteil2019. (c) (Top) Absorption in a natural Cu$_2$O crystal resolving excitonic resonances for large principal quantum numbers. (d) Formation of Rydberg exciton polaritons under strong coupling regime for n=3,..,6. Panels c - d are reproduced with permission from Ref. orfanakis2022 (e) Rabi splitting vs. exciton density and pump fluence is shown for different principal quantum numbers $n$, revealing an increase in $n$-dependent nonlinear coefficient, reproduced with permission from Ref. Makhonin2024. (f) A bi-layer MoS2 coupled to Fabry-Perot microcavity. (Bottom Left) Interlayer excitons with permanent out-of-plane dipole and strong, long-range interactions. (g) Polariton dispersion showing multiple coupled excitonic species. (h) Interlayer (dipolar) polaritons exhibiting enhanced nonlinearity compared to neutral exciton polaritons, evident in low density reduction of apparent Rabi splitting (panels f - h adapted with permission from Ref. Datta2022). (i) Moiré polariton system formed by exciton confined in a moiré lattice, coupled to cavity. (j) Nonlinear enhancement of moiré excitons over intralayer exciton polaritons, (panels i - j are reproduced with permission from Ref. Zhang2021).
• Figure 5: State of the art generation of Graph States and applications of many-body entangled states. (a-h) Generation of cluster and graph states from QDs. (a) Negatively charged QD in the center of a connected pillar optical cavity, (b) single InGaAs QD with GaAs barriers, (c) QD spectral emission, (d) Energy levels and optical selection rules of the negatively charged QD in the presence of a small (<100 mT) transverse magnetic field. Panels a - d are reproduced with permission from Ref. coste2023high. (e) cluster state generation using sequential Hadamard and CNOT gates, (f) QD spin configurations, optical transitions, and their detection used in the measurements, (g) DM represents a dichroic mirror and the magnetic field is applied along the $x$-direction, the states refer to the hole, trion, and excited trion states, (h) the measured (error bars) and calculated (coloured lines) cluster state witnesses. Panels e - h are reproduced with permission from Ref. cogan2023deterministic. (i) (Left) The application of many-body entangled states for quantum-enhanced sensing of an unknown phase (see pezze2018quantum). (Right) Superradiant emission allows for detection that surpasses the shot noise level, image adapted with permission from Ref. paulisch_quantum_2019. (j) Graph states as resource states for quantum communication and quantum computation, generated by specialized quantum emitters, such as QDs, adapted with permission from Ref. zhan2023performance. (k) The presence of long-range interactions between qubits allows for performing quantum simulation of complex many-body systems.