Decoherence effects on quantum control by reverse optimized pulse sequences

Tracking control of two qubit entanglement using piecewise time-independent method

“…For the specific examples of S(t) used in this work, we have chosen to minimize resources like the control field and computational time, choosing functions with slow variations between each time interval. We used the functions arctan or exp which have already being tested in the literature for tracking control [43]. If we choose targets with rapid variations (like delta distribution or step functions), the control method may find a theoretical solution where the response time required to the control field is not possible to obtain in the lab conditions [79].…”

“…It is essential to highlight that we chose the initial state to discuss the entanglement creation and to compare results between two distinct quantum control methods, the piecewise time-independent quantum control and the quantum-jump-based feedback control. The initial state was chosen to compare our results with those obtained in [43], which had a good acceptance in the related scientific community. On the other hand, in section 6.3, we use the simplest state from an experimental point of view, when both qubits are in the ground state, |ψ 0 〉=|g (1) 〉⊗|g (2) 〉.…”

“…As explained in section 3, the functional forms of S(t) used in this work, are slow variations functions between each time interval. We used functions arctan and exponential which have already being tested in the literature for tracking control [43]. The specific numbers which appear as amplitudes in S(t), they were chosen small enough to allow values of the control parameters which are experimentally reproducible.…”

“…Proposals and ideas about how to avoid the effects of decoherence are of central importance for the controlled dynamical evolution of open quantum systems. Several approaches have been put forward to reduce the effects of decoherence, including quantum Zeno effect [37], quantum error correction code [38], decoherence-free subspaces [39], dynamical decoupling [40], quantum feedback control [41,42], or reverse optimized pulse sequences [43]. For a complete review of the control in open quantum systems, we refer to [44,45].…”

Dissipative Dynamics of Laser-Induced Torsional Coherences

“…Coherent quantum control in dissipative environments has been a topic of intense scientific interest for over a decade, − in part because most practical applications envisioned will involve a dissipative medium, in part due to our understanding that open systems behave fundamentally differently from closed systems when subject to a control field, and in part due to the conceptual and practical connection of quantum control with quantum information, where maintenance of coherence is critical. − In particular, much effort has been devoted to understanding decoherence processes by developing better models and approximations, with the aim of extending the temporal window between coherent excitation and loss of control due to decoherence. ,, Low temperatures, optimization schemes, − ,− and careful system design can all extend the time scale over which coherent control is feasible. Much better studied, and of no less interest than the control problem, are the physics of relaxation and decoherence themselves. ,, From this perspective, torsional coherences offer an interesting model, which is sufficiently complex to exhibit a rich spectrum of phenomena (vide infra) yet offers the simplicity of 1D systems and the transferability of conclusions that characterizes rotational coherences.…”