Imaging non-radiative point defects buried in quantum wells using cathodoluminescence

(2021)

Authors:

Thomas Weatherley, Wei Liu, Vitaly Osokin, Duncan Alexander, Robert Taylor, Jean-François Carlin, Raphaël Butté, Nicolas Grandjean

Resonantly pumped bright triplet exciton lasing in caesium lead bromide perovskites

University of Oxford (2021)

Authors:

Guanhua Ying, Tristan Farrow, Atanu Jana, Vitaly Osokin, Hanbo Shao, Youngsin Park, Robert A Taylor

Abstract:

The research looks into the lasing phenomenon from the tetragonally symmetric CsPbBr3 perovskite nanocrystals. The emission has been demonstrated to originate from the triplet state via polarisation and lifetime verifications. A resonantly pumped excitation source has been adopted to tune the inter-level transition resonantly, which significantly enhances the emission characteristics. The data follows the order of the figures contained in the corresponding paper and a comment in each data file explains what each column of the data stands for. The data files cover all the experimental results presented in the main text of the paper.

Simulating molecules on a cloud-based 5-qubit IBM-Q universal quantum computer

Communications Physics Nature Research 20 (2021)

Authors:

S. Leontica, F. Tennie, T. Farrow*

Abstract:

Simulating the behaviour of complex quantum systems is impossible on classical supercomputers due to the exponential scaling of the number of quantum states with the number of particles in the simulated system. Quantum computers aim to break through this limit by using one quantum system to simulate another quantum system. Although in their infancy, they are a promising tool for applied fields seeking to simulate quantum interactions in complex atomic and molecular structures. Here we show an efficient technique for transpiling the unitary evolution of quantum systems into the language of universal quantum computation using the IBM quantum computer and show that it is a viable tool for compiling near-term quantum simulation algorithms. We develop code that decomposes arbitrary 3-qubit gates and implement it in a quantum simulation first for a linear ordered chain to highlight the generality of the approach, and second, for a complex molecule. Here we choose the Fenna-Matthews-Olsen (FMO) photosynthetic protein because it has a well characterised Hamiltonian and presents a complex dissipative system coupled to a noisy environment that helps to improve the efficiency of energy transport. The method can be implemented in a broad range of molecular and other simulation settings.

Two-photon Laser-written Photoalignment Layers for Patterning Liquid Crystalline Conjugated Polymer Orientation

Advanced Functional Materials Wiley (2020)

Authors:

STEPHEN MORRIS, Patrick SALTER, Robert TAYLOR, Steve ELSTON, Donal BRADLEY

Excitation and temperature dependence of the broad gain spectrum in GaAs/AlGaAs quantum rings

Applied Physics Letters AIP Publishing 117:21 (2020) 213101

Authors:

Juyeong Jang, Seunghwan Lee, Minju Kim, Sunwoo Woo, Inhong Kim, Jihoon Kyhm, Jindong Song, Robert Taylor, Kwangseuk Kyhm

Abstract:

We have employed a variable stripe length method in order to measure the optical gain of GaAs/AlGaAs quantum rings. Although the large lateral diameter of quantum rings (∼ 50 nm) with a few nm size distribution is expected to cause a small spectral inhomogeneity (∼ 1 %), a broad gain width (∼ 300 meV) was observed. This result was attributed to a variation of the vertical heights and variations in localized states that exhibit crescent shaped wavefunctions, whereby the energy levels are distributed over a broad spectral range. When the excitation intensity is decreased, irregular peaks appear in the gain spectrum gradually. Similar phenomena were also observed with increased temperature. We conclude that excited carriers in quantum rings are distributed stochastically at various localized states, and the population inversion is sensitive to excitation intensity and temperature.