Long-Lived Quasistationary Coherences in aV-type System Driven by Incoherent Light

Abstract

We present a theoretical study of noise-induced quantum coherences in a model three-level V-type system interacting with incoherent radiation, an important prototype for a wide range of physical systems ranging from trapped ions to biomolecules and quantum dots. By solving the quantum optical equations of motion, we obtain analytic expressions for the noise-induced coherences and show that they exhibit an oscillating behavior in the limit of large excited level spacing Δ (Δ/γ≫1, where γ is the radiative decay width). Most remarkably, we find that in the opposite limit of small level spacing Δ/γ≪1, appropriate for large molecules, (a) the coherences can survive for an extremely long time τ=(2/γ)(Δ/γ)^{-2} before eventually decaying to zero, and (b) coherences at short times can be substantial. We further show that the long-lived coherences can survive environmental relaxation and decoherence, suggesting implications to the design of quantum heat engines and to incoherent light excitation of biological systems.

Partial secular Bloch-Redfield master equation for incoherent excitation of multilevel quantum systems

“…localization properties) determines the photoreaction efficiency or quantum yield 29 . In the opposite regime of non-orthogonal transition dipoles, we observe nontrivial dynamical effects due to the Agarwal-Fano interference 19 , prior to long time relaxation to energy eigenstates.…”

“…[8][9][10][11], an entirely different kind of quantum coherence among the excited states is known to arise [12][13][14][15][16][17][18] , and persist for a long time 19 under incoherent light illumination. These coherences are due to the Agarwal-Fano (AF) interference between different incoherent light-induced transition pathways 12,18,20,21 , and have much in common with previously explored quantum optical phenomena such as vacuum-induced coherence, lasing without inversion, electromagnetically induced transparency, and quantum control 18,19,22 . This kind of noise-induced coherence has recently attracted much interest in view of its potential to enhance the efficiency of quantum heat engines, both natural and artificially designed 13,14,16 .…”

Coherence of mechanical oscillators mediated by coupling to different baths

“…The system-bath coupling Hamiltonian (II.4,II.5)) is written in the original basis as 15) while in the normal mode basis ((…”

“…Recent experimental studies [37][38][39] have demonstrated the feasibility of coupling various quantum systems to non-equilibrium baths, and of tailoring the environmental degrees of freedom. Recent theoretical analysis [15] of a V-type molecular system showed the possibility of long-lived coherences despite noise-induced decoherence, and ref. [16] reports the emergence of steady-state entanglement in the case of finite dimensional coupled systems such as superconducting qubits or quantum dots.…”

“…Therefore, their dynamics are treated as a quantum open system [8][9][10][11][12][13]. The motivation for a fundamental study of dissipation and decoherence by environmental degrees of freedom is bolstered by the theoretical [14][15][16][17] and experimental [18,19] potential to engineer the properties of the environmental bath. Quantum brownian motion [8,9,[20][21][22][23][24][25]] provides a paradigmatic model to study the dynamics of open quantum systems.…”