Generating indistinguishable photons from a quantum dot in a noisy environment

Abstract

Single photons from semiconductor quantum dots are promising resources for linear optical quantum computing, or, when coupled to spin states, quantum repeaters. To realize such schemes, the photons must exhibit a high degree of indistinguishability. However, the solid-state environment presents inherent obstacles for this requirement as intrinsic semiconductor fluctuations can destroy the photon indistinguishability. Here, we demonstrate that resonant excitation of a quantum dot with a narrow-band laser generates near transform limited power spectra and indistinguishable photons from a single quantum dot in an environment with many charge-fluctuating traps. The specificity of the resonant excitation suppresses the excited state population in the quantum dot when it is detuned due to spectral fluctuations. The dynamics of this process lead to flickering of the emission over long time scales (>5 μs) and reduces the time-averaged count rates. Nevertheless, in spite of significant spectral fluctuations, high visibility two-photon interference can be achieved. This approach is useful for quantum dots with nearby surface states in processed photonic structures and quantum emitters in emerging platforms, such as two-dimensional semiconductors.

Spectral diffusion time scales in InGaN/GaN quantum dots

“…However, III-nitride QDs are currently known to suffer from severe spectral diffusion caused by strong Coulomb interactions between QD-confined charges and itinerant charges in the surrounding environment. [22][23][24][25][26][27] This spectral diffusion will severely limit (and possibly negate) the possibility of indistinguishable photon generation [28][29][30][31] from these structures, and thus demands a detailed investigation, particularly with regard to the time scales on which it occurs.…”

Searching for interstellar quantum communications

“…If a quantum transmitter is difficult to build, it would be advantageous to use a classical coherent light source (a laser) and let the receiver do the quantum lift. On the other hand, if pair photons can readily be made, e.g., with semiconductor quantum dots (Santana et al 2017), they could be used onboard a spacecraft.…”

Role of generalized parity in the symmetry of the fluorescence spectrum from two-level systems under periodic frequency modulation

“…Next, we discuss the parity phenomenon of the Floquet states resulting from Eq. (5). We consider the behavior of the Floquet states under the generalized parity transformation P G , which is defined as…”

“…, σ x |ũ α (t + T /2) satisfies the same differential equation as |ũ α (t) because of Eq. (5). Recalling the uniqueness of solutions of the differential equations, in such cases we must have…”