Six Basic Principles of the Stochastic Limit

A. O. Bolivar

Khavtgain Namsrai

Zahid Zakir

Nelson's stochastic mechanics is derived as a consequence of the basic physical principles such as the principle of relativity of observations and the invariance of the action quantum.The unitary group of quantum mechanics is represented as the transformations of the systems of perturbing devices.It is argued that the physical spacetime has a stochastic nature and that quantum mechanics in Nelson's formulation correctly describes this stochasticity.

Luigi Accardi, Igor Vasil'evich Volovich, Yun Gang Lu

Eugene Mamontov, M. Willander

The limits of applicability of many classical (non-quantum-mechanical) theories are not sharp. These theories are sometimes applied to the problems which are, in their nature, not very well suited for that. Two of the most widely used classical approaches are the theory of diffusion stochastic process and Itô's stochastic differential equations. It includes the Brownian-motion treatment as the basic particular case. The present work shows that, for quantum-mechanical reasons, the diffusion parameter of a Brownian particle cannot be arbitrarily small since it has a nonzero minimum value. This fact leads to the version of Heisenberg's uncertainty principle for a Brownian particle which is obtained in the precise mathematical form of a limit inequality. These quantitative results can help to properly apply the theories associated with Brownian-particle modelling. The consideration also discusses a series of works of other authors.

A. Tasnim Aynul, C. Li, L. Cruz Rodriguez +1 more

We propose and demonstrate the Kramers-Henneberger KH) atom as a novel qubit platform for ultrafast single-qubit gate operations. In the KH frame, the time-averaged strong laser field engineers a double-well potential whose two lowest eigenstates define the qubit basis, so that the computational structure is created and maintained by the driving field itself. A weak resonant control field drives coherent gate operations: full time-dependent Schrödinger equation simulations with the complete time-dependent KH potential confirm a Z gate and S gate of the order of femtoseconds, six orders of magnitude faster than laser-driven superconducting qubit gates. Decoherence characterisation gives longer decoherence times than those required for the gate operations. The complete six-gate single-qubit set is demonstrated in the time-averaged two-level limit, with strong agreement between the full and time-averaged descriptions confirming that fidelity is limited by structured leakage rather than stochastic decoherence. In principle, this is an error channel suppressible through pulse engineering. These results constitute the first demonstration of coherent single-qubit gates in a strong-field setting, with a clear pathway toward attosecond-scale operations.