Focus on coherent control of complex quantum systems

Abstract

The rapid growth of quantum information sciences over the past few decades has fueled a corresponding rise in high profile applications in fields such as metrology, sensors, spintronics, and attosecond dynamics, in addition to quantum information processing. Realizing this potential of today's quantum science and the novel technologies based on this requires a high degree of coherent control of quantum systems. While early efforts in systematizing methods for high fidelity quantum control focused on isolated or closed quantum systems, recent advances in experimental design, measurement and monitoring, have stimulated both need and interest in the control of complex or large scale quantum systems that may also be coupled to an interactive environment or reservoir. This focus issue brings together new theoretical and experimental work addressing the formulation and implementation of quantum control for a broad range of applications in quantum science and technology today.

Coherent electronic and nuclear dynamics in a rhodamine heterodimer–DNA supramolecular complex

“…Long time (1 ps) persisting oscillations have been recorded in the 2D spectra of several biological complexes and have been interpreted as due to quantum coherent mechanisms of energy transport. [3][4][5][6][7] The persistence of these oscillations for times much longer than what is estimated by spectral line widths, predicting electronic dephasing times not longer than 100 fs, 8 initiated a lively debate about their origin and the mechanism enabling this persistence. [9][10][11][12][13][14] Does the coupling with vibrations extend, sustain or destroy electronic coherences is still an open question.…”

Order from chaos in quantum walks on cyclic graphs

“…This also means that its reverse process is also possible, i.e., breaking a periodic quantum signal into two or more quantum chaotic signals. The periodic probability distribution generated from two chaotic ones seen in discrete time quantum walks on cyclic graphs are of great interest in designing new quantum algorithms, quantum cryptology as well as in development of quantum chaos control theory [19]. Finally, there have been recent reports on development of quantum image encryption techniques via chaotic quantum walks on cyclic graphs [20].…”

“…In fact the equations obtained for a 5− cycle graph are identical to that shown in Eqs. (12)(13)(14)(15)(16)(17)(18)(19)(20). This is no doubt a consequence of the properties of the cyclic graph itself as well as that of the commensurate Fourier matrix F.…”

Simulating Quantum Materials with Digital Quantum Computers

“…Examples include phase qubits [75,76], flux qubits [77], charge qubits [78], transmons [79,80], Xmons [81], and gatemons [82]. Qubits are typically coupled to electromagnetic cavities and their control and readout is performed by microwave pulses into these cavities [83,84,85,86,87,88,89,90,91,92,93,94,95,96]. There has been rapid improvement in this technology in the past decade [97,98].…”