Repository logo
 

A Single-photon Source Based on a Lateral n-i-p Junction Driven by a Surface Acoustic Wave


Type

Thesis

Change log

Authors

Hsiao, Tzu-Kan 

Abstract

Single-photon sources are essential building blocks in quantum photonic networks, where quantum-mechanical properties of photons are utilised to achieve quantum technologies such as quantum cryptography and quantum computing. In this thesis, a single-photon source driven by a surface acoustic wave (SAW) is developed and characterised. This single-photon source is based on a SAW-driven lateral n-i-p junction in a GaAs quantum-well structure. On this device, the lateral n-i-p junction is formed by gate-induced electrons and holes in two adjacent regions. The SAW potential minima create dynamic quantum dots in a 1D channel between these two regions, and are able to transport single electrons to the region of holes along the channel. Single-photon emission can therefore be generated as these electrons consecutively recombine with holes.

After characterisation and optimisation in four batches of devices, clear SAW-driven charge transport and the corresponding electroluminescence (EL) can be observed on an optimised SAW-driven n-i-p junction. Time-resolved measurements have been carried out to study the dynamics of SAW-driven electrons. Time-resolved EL signals indicate that a packet of electrons is transported to the region of holes in each SAW minimum. In addition, the carrier lifetime of SAW-driven electrons in the region of holes is shown to be ∼100 ps, which is much shorter than the SAW period of 860 ps. Hence, it is promising to observe single-photon emission in the optimised device.

In order to test single-photon emission, a Hanbury Brown-Twiss experimental setup has been employed to record an autocorrelation histogram of the SAW-driven EL signal at the single-electron regime. Suppression of autocorrelation coincidences at time delay Δt=0 is evidence of photon antibunching. By fitting theoretical functions describing the SAW-driven EL signal, it is found that the second-order correlation function shows g(2)(0)=0.39±0.05, which is lower than the common criterion for a single-photon source g(2)(0)<0.5. Moreover, theoretical calculation and simulation suggest that, if a constant background signal can be filtered out, ∼80% of the SAW-driven EL is single-photon emission.

Description

Date

2018-06-01

Advisors

Ford, Chris

Keywords

surface acoustic wave, single-photon source, quantum information, quantum computing, undoped GaAs quantum well, lateral n-i-p junction

Qualification

Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge
Sponsorship
Cambridge Overseas Trust, Taiwan Government, Robinson college, Cavendish Laboratory, Cambridge Student Registry.

Collections