NONLOCALITY DYNAMICS INDUCED BY A LAMB–DICKE NONLINEARITY IN TWO DIPOLE-COUPLED TRAPPED IONS UNDER INTRINSIC DECOHERENCE

In this paper, we explore the nonlinear dynamics of two dipole-coupled-trapped ions in the Lamb–Dicke regime. The dynamics of the generated two-trapped-ions correlations under intrinsic decoherence is quantified by Bell function, the uncertainty-induced nonlocality, and the concurrence. We investigate the effects of the Lamb–Dicke nonlinearity, the intrinsic decoherence, and the two-trapped-ions coupling. It is found that the two-trapped-ions state has different nonlocal correlations. These correlations can be controlled. In the absence of decoherence, the nonlocal correlations can be enhanced by the Lamb–Dicke nonlinearity and the two-trapped-ions coupling. The stable value and the sudden death-birth phenomenon of the entanglement can be apperceived due to the increase of the Lamb–Dicke nonlinearity. The intrinsic decoherence reduces and stabilizes the nonlocal correlations. They are more pronounced with large Lamb–Dicke values. The decoherence effects are reduced by the strong Lamb–Dicke nonlinearity.

Macroscopic Nonlocal Correlations in the Data Obtained in New Deep-Water Measurements

Macroscopic nonlocal correlations of random dissipative processes manifest at extremely low frequencies, meaning that observing them involves long-term experiments that maintain highly stable conditions in the detectors. This motivated the Baikal experiment, which investigates correlations between helio-geophysical processes featuring a high random component and test random processes in the detectors installed at various depths in the lake and at a remote land observatory. In the latest year-long experiment series, we focused on the data coming from the bottom detector, the one best protected from classical local interference. The results confirm that correlation with solar activity dominates the detector signal and, at the same time, it is easy to distinguish a forward correlation with thermodynamic activity in the upper active layer of Lake Baikal. The presence of this significant forward nonlocal correlation made it possible to simulate a realistic forecast of the active layer temperature a month ahead. We also detected an unusual diurnal variation in the relatively short-period spectrum of deep-water detector signals, presumably associated with the reemission of solar radiation by the Earth surface

Separation of quantum, spatial quantum, and approximate quantum correlations

Quantum nonlocal correlations are generated by implementation of local quantum measurements on spatially separated quantum subsystems. Depending on the underlying mathematical model, various notions of sets of quantum correlations can be defined. In this paper we prove separations of such sets of quantum correlations. In particular, we show that the set of bipartite quantum correlations with four binary measurements per party becomes strictly smaller once we restrict the local Hilbert spaces to be finite dimensional, i.e., Cq(4,4,2,2)≠Cqs(4,4,2,2). We also prove non-closure of the set of bipartite quantum correlations with four ternary measurements per party, i.e., Cqs(4,4,3,3)≠Cqa(4,4,3,3).

Ultra-stable charging of fast-scrambling SYK quantum batteries

Collective behavior strongly influences the charging dynamics of quantum batteries (QBs). Here, we study the impact of nonlocal correlations on the energy stored in a system of N QBs. A unitary charging protocol based on a Sachdev-Ye-Kitaev (SYK) quench Hamiltonian is thus introduced and analyzed. SYK models describe strongly interacting systems with nonlocal correlations and fast thermalization properties. Here, we demonstrate that, once charged, the average energy stored in the QB is very stable, realizing an ultraprecise charging protocol. By studying fluctuations of the average energy stored, we show that temporal fluctuations are strongly suppressed by the presence of nonlocal correlations at all time scales. A comparison with other paradigmatic examples of many-body QBs shows that this is linked to the collective dynamics of the SYK model and its high level of entanglement. We argue that such feature relies on the fast scrambling property of the SYK Hamiltonian, and on its fast thermalization properties, promoting this as an ideal model for the ultimate temporal stability of a generic QB. Finally, we show that the temporal evolution of the ergotropy, a quantity that characterizes the amount of extractable work from a QB, can be a useful probe to infer the thermalization properties of a many-body quantum system.