Lata Kh Joshi

Bounded-Error Quantum Simulation via Hamiltonian and Lindbladian Learning

Tristan Kraft [1,2,3], Manoj K. Joshi [4,5], William Lam [6], Tobias Olsacher [7,3,4], Florian Kranzl [4,5], Johannes Franke [4,5], Lata Kh Joshi [8], Rainer Blatt [4,5], Augusto Smerzi [9,10,6,11], Daniel Stilck França, Benoît Vermersch, Barbara Kraus [1,2], Christian F. Roos [4,5], Peter Zoller [3,4]

Abstract

Analog Quantum Simulators offer a route to exploring strongly correlated many-body dynamics beyond classical computation, but their predictive power remains limited by the absence of quantitative error estimation. Establishing rigorous uncertainty bounds is essential for elevating such devices from qualitative demonstrations to quantitative scientific tools. Here we introduce a general framework for bounded-error quantum simulation, which provides predictions for many-body observables with experimentally quantifiable uncertainties. The approach combines Hamiltonian and Lindbladian Learning--a statistically rigorous inference of the coherent and dissipative generators governing the dynamics--with the propagation of their uncertainties into the simulated observables, yielding confidence bounds directly derived from experimental data. We demonstrate this framework on trapped-ion quantum simulators implementing long-range Ising interactions with up to 51 ions, and validate it where classical comparison is possible. We analyze error bounds on two levels. First, we learn an open-system model from experimental data collected in an initial time window of quench dynamics, simulate the corresponding master equation, and quantitatively verify consistency between theoretical predictions and measured dynamics at long times. Second, we establish error bounds directly from experimental measurements alone, without relying on classical simulation--crucial for entering regimes of quantum advantage. The learned models reproduce the experimental evolution within the predicted bounds, demonstrating quantitative reliability and internal consistency. Bounded-error quantum simulation provides a scalable foundation for trusted analog quantum computation, bridging the gap between experimental platforms and predictive many-body physics. The techniques presented here directly extend to digital quantum simulation.

Measuring full counting statistics in a trapped-ion quantum simulator

Lata Kh Joshi [1], Filiberto Ares [1], Manoj K. Joshi [2,3], Christian F. Roos [2,3], Pasquale Calabrese [1,4]

Abstract

In quantum mechanics, the probability distribution function (PDF) and full counting statistics (FCS) play a fundamental role in characterizing the fluctuations of quantum observables, as they encode the complete information about these fluctuations. In this letter, we measure these two quantities in a trapped-ion quantum simulator for the transverse and longitudinal magnetization within a subsystem. We utilize the toolbox of classical shadows to postprocess the measurements performed in random bases. The measurement scheme efficiently allows access to the FCS and PDF of all possible operators on desired choices of subsystems of an extended quantum system.

Observing the quantum Mpemba effect in quantum simulations

Lata Kh Joshi [1,2,3], Johannes Franke [1,4], Aniket Rath [5], Filiberto Ares [3], Sara Murciano [6], Florian Kranzl [1,4], Rainer Blatt [1,4], Peter Zoller [1,2,5], Benoît Vermersch, Pasquale Calabrese [3,7], Christian F. Roos [1,4], Manoj K. Joshi [1,4]

Abstract

The non-equilibrium physics of many-body quantum systems harbors various unconventional phenomena. In this study, we experimentally investigate one of the most puzzling of these phenomena -- the quantum Mpemba effect, where a tilted ferromagnet restores its symmetry more rapidly when it is farther from the symmetric state compared to when it is closer. We present the first experimental evidence of the occurrence of this effect in a trapped-ion quantum simulator. The symmetry breaking and restoration are monitored through entanglement asymmetry, probed via randomized measurements, and postprocessed using the classical shadows technique. Our findings are further substantiated by measuring the Frobenius distance between the experimental state and the stationary thermal symmetric theoretical state, offering direct evidence of subsystem thermalization.