We investigate the feasibility of identifying many-body localization in semiconductor quantum dot arrays within current experimental capabilities. Using an extended Fermi-Hubbard model parameterized by realistic device conditions, we analyze the phase diagram through a set of observables with varying experimental accessibility. Our results demonstrate that signatures of MBL can, in principle, be accessed in present-day quantum dot platforms. Crucially, we show that the widely used imbalance fails to distinguish between interaction-induced freezing and genuine localization, highlighting the importance of carefully selecting and interpreting experimental probes. We identify observables that can reliably distinguish genuine MBL from interaction-induced effects, thereby establishing practical criteria for detecting localization in realistic quantum dot arrays.
We investigate the feasibility of identifying many-body localization in semiconductor quantum dot arrays within current experimental capabilities. Using an extended Fermi-Hubbard model parameterized by realistic device conditions, we analyze the phase diagram through a set of observables with varying experimental accessibility. Our results demonstrate that signatures of MBL can, in principle, be accessed in present-day quantum dot platforms. Crucially, we show that the widely used imbalance fails to distinguish between interaction-induced freezing and genuine localization, highlighting the importance of carefully selecting and interpreting experimental probes. We identify observables that can reliably distinguish genuine MBL from interaction-induced effects, thereby establishing practical criteria for detecting localization in realistic quantum dot arrays.
The phenomenon of many-body localized (MBL) systems has attracted significant interest in recent years, for its intriguing implications from a perspective of both condensed-matter and statistical physics: they are insulators even at non-zero temperature and fail to thermalize, violating expectations from quantum statistical mechanics. What is more, recent seminal experimental developments with ultra-cold atoms in optical lattices constituting analog quantum simulators have pushed many-body localized systems into the realm of physical systems that can be measured with high accuracy. In this work, we introduce experimentally accessible witnesses that directly probe distinct features of MBL, distinguishing it from its Anderson counterpart. We insist on building our toolbox from techniques available in the laboratory, including on-site addressing, super-lattices, and time-of-flight measurements, identifying witnesses based on fluctuations, density–density correlators, densities, and entanglement. We build upon the theory of out of equilibrium quantum systems, in conjunction with tensor network and exact simulations, showing the effectiveness of the tools for realistic models.
Many-body localization (MBL) freezes the dynamics of a disordered quantum interacting system, inhibiting thermalization and resulting in a persistent memory of the initial state. Here, with the help of extensive numerical simulations, the authors find slow decay of the imbalance, a quantity often employed in experimental studies of MBL, even though the disorder strength considerably exceeds the current estimates of the position of the MBL transition. This suggests a slow approach to thermal equilibrium and identifies challenges for unequivocal numerical and experimental demonstrations of MBL.
The phenomenon of many-body localised (MBL) systems has attracted significant interest in recent years, for its intriguing implications from a perspective of both condensed-matter and statistical physics: they are insulators even at non-zero temperature and fail to thermalise, violating expectations from quantum statistical mechanics. What is more, recent seminal experimental developments with ultra-cold atoms in optical lattices constituting analog quantum simulators have pushed many-body localised systems into the realm of physical systems that can be measured with high accuracy. In this work, we introduce experimentally accessible witnesses that directly probe distinct features of MBL, distinguishing it from its Anderson counterpart. We insist on building our toolbox from techniques available in the laboratory, including on-site addressing, super-lattices, and time-of-flight measurements, identifying witnesses based on fluctuations, density-density correlators, densities, and entanglement. We build upon the theory of out of equilibrium quantum systems, in conjunction with tensor network and exact simulations, showing the effectiveness of the tools for realistic models.
Many-body-localization (MBL) transitions are studied in a family of single-spin-flip spin- 1 2 models, including the one-dimensional (1D) chain with nearest-neighbor interactions, the quantum dot (QD) model with all-to-all pair interactions, and the quantum random energy model (QREM). We investigate the generalized imbalance that characterizes propagation in Fock space out of an initial basis state and, at the same time, can be efficiently probed by real-space measurements. For all models considered, the average imbalance and its quantum and mesoscopic fluctuations provide excellent indicators for the position of the MBL transition W c ( n ) , where n is the number of spins. Combining these findings with earlier results on level statistics, we determine phase diagrams of the MBL transitions in the n − W plane. Our results provide evidence for a direct transition between the ergodic and MBL phases for each of the models, without any intermediate phase. For QREM and QD model, W c ( n ) grows as a power law of n (with logarithmic corrections), in agreement with analytical predictions W c QREM ( n ) ∼ n 1 / 2 ln n and W c QD ( n ) ≳ n 3 / 4 ln 1 / 2 n . This growth is in stark contrast to the 1D model, where W c ( n ) is essentially independent of n , consistent with the analytic expectation W c 1 D ( n → ∞ ) = const . We also determine the scaling of the transition width Δ W ( n ) / W c ( n ) and estimate the system size n needed to study the asymptotic scaling behavior. Although the corresponding values of n are larger than those accessible to exact simulations on a classical computer, they are within the reach of quantum simulators. Our results indicate feasibility of experimental studies of n − W phase diagrams and scaling properties of MBL transitions in models of 1D and QD type and in their extensions to other spatial geometry or distance-dependent interactions.
We propose a device for studying the Fermi-Hubbard model with long-range Coulomb interactions using an array of coupled quantum dots defined in a semiconductor two-dimensional electron-gas system. Bands above the lowest energy band are used to form the Hubbard model, so that a high average electron density may be used to implement the device. We find that depending on the average electron density, the system is well described by a one- or two-band Hubbard model. Our device design enables the control of the ratio of the Coulomb interaction to the kinetic energy of the electrons independently to the filling of the quantum dots, such that a large portion of the Hubbard phase diagram may be probed. Estimates of the Hubbard parameters suggest that a metal-Mott insulator quantum phase transition and a d-wave superconducting phase should be observable using current technologies.
We study time dynamics of 1D disordered Heisenberg spin-1/2 chain focusing on a regime of large system sizes and a long time evolution. This regime is relevant for observation of many-body localization (MBL), a phenomenon that is expected to freeze the dynamics of the system and prevent it from reaching thermal equilibrium. Performing extensive numerical simulations of the imbalance, a quantity often employed in the experimental studies of MBL, we show that the regime of a slow power-law decay of imbalance persists to disorder strengths exceeding by at least a factor of 2 the current estimates of the critical disorder strength for MBL. Even though we investigate time evolution up to few thousands tunneling times, we observe no signs of the saturation of imbalance that would suggest freezing of system dynamics and provide a smoking gun evidence of MBL. We demonstrate that the situation is qualitatively different when the disorder is replaced by a quasiperiodic potential. In this case, we observe an emergence of a pattern of oscillations of the imbalance that is stable with respect to changes in the system size. This suggests that the dynamics of quasiperiodic systems remain fully local at the longest time scales we reach provided that the quasiperiodic potential is sufficiently strong. Our study identifies challenges in an unequivocal experimental observation of the phenomenon of MBL.