arXiv subjects

John Henry Reina

Publications and source records attributed to John Henry Reina.

3 recordsLinked to original sources

arXiv2025

Machine learning non-Markovian two-level quantum noise spectroscopy

We develop machine learning models for the automated characterization of quantum noise spectroscopy for non-Hermitian two-level systems. We use the Random Forest, Support Vector and Feed-Forward Neural Network regression algorithms to perform a highly accurate regression of the two-level system-bath coupling strength. High accuracy Ohmicity classification was implemented to provide a complete characterization of the spectral density function. We define a time-averaged trace-distance metric to feed the machine learning algorithms which, together with numerically exact populations as inputs, produce a highly accurate non-Markovian regression spanning the transition from fast to slow baths and from weak to strong coupling regimes of the interaction. The dynamics database of the non-Hermitian systems has been built up within the independent spin-boson and pure dephasing model.

quant-ph↗

arXiv2009

Coherent control of an effective two-level system in a non-Markovian biomolecular environment

We investigate the quantum coherent dynamics of an externally driven effective two-level system subjected to a slow Ohmic environment characteristic of biomolecular protein-solvent reservoirs in photosynthetic light harvesting complexes. By means of the numerically exact quasi adiabatic propagator path integral (QUAPI) method we are able to include non-Markovian features of the environment and show the dependence of the quantum coherence on the characteristic bath cut-off frequency omega_c as well as on the driving frequency omega_l and the field amplitude A. Our calculations extend from the weak coupling regime to the incoherent strong coupling regime. In the latter case, we find evidence for a resonant behaviour, beyond the expected behaviour, when the reorganization energy E_r coincides with the driving frequency. Moreover, we investigate how the coherent destruction of tunneling within the two-level system is influenced by the non-Markovian environment.

cond-mat.mes-hall↗

arXiv2004

Optical Schemes for Quantum Computation in Quantum Dot Molecules

We give three methods for entangling quantum states in quantum dots. We do this by showing how to tailor the resonant energy (Foerster-Dexter) transfer mechanisms and the biexciton binding energy in a quantum dot molecule. We calculate the magnitude of these two electrostatic interactions as a function of dot size, interdot separation, material composition, confinement potential and applied electric field by using an envelope function approximation in a two-cuboid dot molecule. In the first implementation, we show that it is desirable to suppress the Foerster coupling and to create entanglement by using the biexciton energy alone. We show how to perform universal quantum logic in a second implementation which uses the biexciton energy together with appropriately tuned laser pulses: by selecting appropriate materials parameters high fidelity logic can be achieved. The third implementation proposes generating quantum entanglement by switching the Foerster interaction itself. We show that the energy transfer can be fast enough in certain dot structures that switching can occur on a timescale which is much less than the typical decoherence times.

quant-ph↗