Entanglement of a laser-driven pair of two-level qubits via its phonon environment

Abstract

The entanglement dynamics of a laser-pumped two-level quantum dot pair is investigated in the steady-state. The closely spaced two-level emitters, embedded in a semiconductor substrate, interact with both the environmental vacuum modes of the electromagnetic field reservoir as well as with the lattice vibrational phonon thermostat. We have found that the entanglement among the pair's components is substantially enhanced due to presence of the phonon subsystem. The reason is phonon induced decay among the symmetrical and antisymmetrical two-qubit collective states and, consequently, the population of the latter one. This also means that through thermal phonon bath engineering one can access the subradiant two-particle cooperative state.

Dephasing-assisted entanglement in a system of strongly coupled qubits

“…These terms do not appear in the local approach, in which Lindblad superoperators are assumed as in the case of non-interacting TLSs [35,37]. Note that in [22] it has been mentioned that the dephasing reservoirs in the case of coupled qubits result in transition between super-and subradiant states. However, in [22] it has been considered stationary entanglement which is created by the external coherent drive.…”

“…Note that in [22] it has been mentioned that the dephasing reservoirs in the case of coupled qubits result in transition between super-and subradiant states. However, in [22] it has been considered stationary entanglement which is created by the external coherent drive. In contrast, here we are interested in the temporal dynamics of the entanglement between two qubits without any external coherent source.…”

“…The problem of entanglement creation in such a system has been investigated in many works [14][15][16][17][18][19][20], and several opportunities to create and conserve entanglement exist. One can enhance the interaction between TLSs in such a way that the ground state of the system becomes entangled [17,20] or use coherent external drive to move the system into the entangled state [21,22]. The use of common reservoirs for two qubits is another way to create entanglement [14,16,18,23].Free space modes of electromagnetic field are an example of common reservoirs for dipole moments of atoms or molecules.…”

Entanglement versus cooling in the system of a driven pair of two-level qubits longitudinally coupled with a boson-mode field

“…Ultra-strong dipole-dipole interacting two-level superconducting flux qubits are naturally entangled through their corresponding environmental reservoir and maximum coherence can be induced too [23]. Furthermore, a pair of moderately dipole-dipole coupled and laser pumped two-level quantum dots get maximal entangled via their environmental phonon thermostat which facilitates also the creation of a subradiant two-qubit state [24].Recently, based on quantum dots systems, a relevant experimental realization of an interconnection among two qubits located five meters apart from each other, via single photons, was reported in Ref. [25].Often to realize quantum states of matter or light one requires ground-state cooled individual or coupled quantum systems, respectively.…”

“…Ultra-strong dipole-dipole interacting two-level superconducting flux qubits are naturally entangled through their corresponding environmental reservoir and maximum coherence can be induced too [23]. Furthermore, a pair of moderately dipole-dipole coupled and laser pumped two-level quantum dots get maximal entangled via their environmental phonon thermostat which facilitates also the creation of a subradiant two-qubit state [24].…”