arXiv subjects

E. Murray

Publications and source records attributed to E. Murray.

5 recordsLinked to original sources

arXiv2026

Automation and Modernisation of Legacy BiSON Solar Observatories with the BiSON:NG Platform

The Birmingham Solar Oscillations Network (BiSON) provides long-term, high-precision Sun-as-a-star radial-velocity observations for helioseismology. While most BiSON sites operate autonomously, two observatories at Observatorio del Teide, Tenerife, and at Mount Wilson Observatory, USA, have historically required daily on-site operation. We present the automation of these sites using the BiSON:NG next-generation observing platform, incorporating compact fibre-fed instrumentation and a modular, microservice-based control and data acquisition architecture. At both locations, new automated optical feeds and a common software framework have been deployed, enabling autonomous operation of the observing subsystems, including guiding, data acquisition, and instrument control, despite markedly different physical and operational constraints. The upgrades demonstrate that modern automation can be successfully integrated within existing and historic observatory infrastructure. Adoption of the BiSON:NG architecture reduces operational overhead, mitigates risks associated with hardware and software obsolescence, and supports sustainable operation of the network over the multi-decade timescales required for helioseismic studies. The flexibility of the architecture also provides a pathway for future deployment of additional small-footprint observatories.

astro-ph.IM↗

arXiv2017

Electrically driven and electrically tunable quantum light sources

Compact and electrically controllable on-chip sources of indistinguishable photons are desirable for the development of integrated quantum technologies. We demonstrate that two quantum dot light emitting diodes (LEDs) in close proximity on a single chip can function as a tunable, all-electric quantum light source. Light emitted by an electrically excited driving LED is used to excite quantum dots the neighbouring diode. The wavelength of the quantum dot emission from the neighbouring driven diode is tuned via the quantum confined Stark effect. We also show that we can electrically tune the fine structure splitting.

cond-mat.mes-hall↗

arXiv2015

Cavity-enhanced coherent light scattering from a quantum dot

Resonant excitation of atoms and ions in macroscopic cavities has lead to exceptional control over quanta of light. Translating these advantages into the solid state with emitters in microcavities promises revolutionary quantum technologies in information processing and metrology. Key is resonant optical reading and writing from the emitter-cavity system. However, it has been widely expected that the reflection of a resonant laser from a micro-fabricated wavelength-sized cavity would dominate any quantum signal. Here we demonstrate coherent photon scattering from a quantum dot in a micro-pillar. The cavity is shown to enhance the fraction of light which is resonantly scattered towards unity, generating anti-bunched indistinguishable photons a factor of 16 beyond the time-bandwidth limit, even when the transition is near saturation. Finally, deterministic excitation is used to create 2-photon N00N states with which we make super-resolving phase measurements in a photonic circuit.

quant-ph↗

arXiv2015

Conditions for entangled photon emission from (111)B site-controlled Pyramidal quantum dots

A study of highly symmetric site-controlled Pyramidal In0.25Ga0.75As quantum dots (QDs) is presented. It is discussed that polarization-entangled photons can be also obtained from Pyramidal QDs of different designs from the one already reported in Juska et al. (Nat. Phot. 7, 527, 2013). Moreover, some of the limitations for a higher density of entangled photon emitters are addressed. Among these issues are (1) a remaining small fine-structure splitting and (2) an effective QD charging under non-resonant excitation conditions, which strongly reduce the number of useful biexciton-exciton recombination events. A possible solution of the charging problem is investigated exploiting a dual-wavelength excitation technique, which allows a gradual QD charge tuning from strongly negative to positive and, eventually, efficient detection of entangled photons from QDs, which would be otherwise ineffective under a single-wavelength (non-resonant) excitation.

quant-ph↗

arXiv2003

Evidence for Toroidal B-Field Structures in BL Lac Objects

If the transverse jet B fields observed in BL Lac objects on parsec scales represent the toroidal component of the jet B fields, this should give rise to rotation-measure gradients across the jets, due to the systematic change in the line-of-sight component of the jet B field. We have found evidence for such rotation-measure gradients in one-third to one-half of the 1 Jy BL Lac objects we have analyzed. We present and discuss these new results, together with some of their implications for our understanding of the parsec-scale jets of AGN.

astro-ph↗