Continuous Quantum Measurements in the Bohmian Framework

Antonio Boulhosa Nassar, Salvador Miret-Artés

Davide Romano

Bohmian mechanics is a realistic interpretation of quantum theory. It shares the same ontology of classical mechanics: particles following continuous trajectories in space through time. For this ontological continuity, it seems to be a good candidate for recovering the classical limit of quantum theory. Indeed, in a Bohmian framework, the issue of the classical limit reduces to showing how classical trajectories can emerge from Bohmian ones, under specific classicality assumptions. In this paper, we shall focus on a technical problem that arises from the dynamics of a Bohmian system in bounded regions; and we suggest that a possible solution is supplied by the action of environmental decoherence. However, we shall show that, in order to implement decoherence in a Bohmian framework, a stronger condition is required (disjointness of supports) rather than the usual one (orthogonality of states).

Carlo Presilla A, Ubaldo Tambini

Antonio Boulhosa Nassar, Salvador Miret-Artés

This Letter proposes an answer to a challenge posed by Bell on the lack of clarity in regards to the dividing line between the quantum and classical regimes in a measurement problem. To this end, a generalized logarithmic nonlinear Schrödinger equation is proposed to describe the time evolution of a quantum dissipative system under continuous measurement. Within the Bohmian mechanics framework, a solution to this equation reveals a novel result: it displays a time constant that should represent the dividing line between the quantum and classical trajectories. It is shown that continuous measurements and damping not only disturb the particle but compel the system to converge in time to a Newtonian regime. While the width of the wave packet may reach a stationary regime, its quantum trajectories converge exponentially in time to classical trajectories. In particular, it is shown that damping tends to suppress further quantum effects on a time scale shorter than the relaxation time of the system. If the initial wave packet width is taken to be equal to 2.8×10(-15) m (the approximate size of an electron), the Bohmian time constant is found to have an upper limit, i.e., τ(Bmax)=10(-26) s.

Wenlin Li

We analyze quantum effects involved in continuous variable synchronization between two self-sustaining resonators in the framework of Bohmian mechanics. Bohmian trajectories provide visual descriptions of significant nonclassical dynamics, which allow us to characterize the level of quantum synchronization more intuitively compared with only utilizing some designed synchronization measures. It is found that in the quantum limit, the Bohmian trajectories will deviate from their corresponding semiclassical limit cycle behavior after they are distorted by the quantum potential. We explore the roles of zero-point fluctuation, superposition, and nonlocal correlation in synchronization dynamics, corresponding to the oscillators in a coherent state, superposition state, and entanglement state, respectively. We also explore the influence of squeezed Hamiltonian on spontaneous synchronization.

E.G. Eberle