Superconductor-Based Quantum-Dot Light-Emitting Diodes: Role of Cooper Pairs in Generating Entangled Photon Pairs

Abstract

Realization of solid-state photon sources which are capable of on-demand generation of entangled single photon pair at a time is highly desired for quantum information processing and communication. A new method to generate entangled single photon pair at a time is proposed employing Cooper-pair-related radiative recombination in a quantum dot (QD).Cooper pairs are bosons and the control of their number states is not easy. The Pauli's exclusion principle on quasi-particles in a discrete state of a QD will regulate the number state of the generated photon pairs in this scheme. The fundamental heterostructures for constructing superconductor-based quantum-dot light-emitting diodes (SQ-LED) and the fundamental operation conditions of SQ-LED will be discussed. The experimental studies on Cooper-pair injection into the related semiconductor structures will be also discussed.

Photon-pair generation based on superconductivity

“…Since Cooper pairs collapse with energy relaxation, the Cooper-pair injection into the QD conduction band should be either resonant injection into a QD energy level with a type-I QD as shown in Fig. 1 or evanescent penetration with a type-II QD [20]. In this review paper, the theoretical treatment of the Cooper-pair radiative recombination is described and is compared with our experimental results.…”

“…The remaining problem is that this is the second-order process and the EPP generation probability is low on the order of 10 −5 of the first-order single photon process [19]. We have proposed another scheme to generate EPPs employing superconductivity [20]. This is fundamentally a light emitting diode (LED) but the n-type electrode is replaced with a superconductor.…”

Observation of enhanced luminescence emitted from InAs quantum dots with direct contact to superconducting niobium stripe

“…It is important to develop the key device to connect the two research fields. We have proposed superconductor-based QD-light-emitting diode (SQLED) [1] as the key device to connect the two research fields. Recently Hayashi et al [2] reported the drastic enhancement of LED light output with superconducting effect with Nb electrode deposited n-type InGaAs/InGaAs/p-type InP quantum well (QW) structure.…”

Time-resolved measurements of Cooper-pair radiative recombination in InAs quantum dots

“…7 We have proposed and have been working on a new method based on superconductors, where QEPPs can be generated through the radiative recombination of Cooper pairs. 8 Electrons in superconductors form Cooper pairs which are spin-singlet entangled pairs. 9 At a superconductor/normalmetal interface, Cooper pairs penetrate into the normal region by the proximity effect.…”