Prof. John Rarity
University of Bristol, Bristol, United Kingdom
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Academic Career Length
24Years (2003-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications4 September 2020 in Science Advances
Journal Article
SJSiddarth Koduru Joshi
Siddarth Koduru JoshiDADjeylan Aktas
Djeylan Aktas
SWSören Wengerowsky
Sören Wengerowsky
MLMartin Lončarić
Martin LončarićSNSebastian Philipp Neumann
Sebastian Philipp NeumannRURupert Ursin
Rupert Ursin
+9
An eight-user fully connected and scalable city-wide quantum communication network can be a basis for the future quantum internet.
7 July 2010 in Physical Review A
Journal Article
ALAnthony Laing
Anthony LaingVSValerio Scarani
Valerio ScaraniJohn RarityJOJeremy L. O’bRien
Jeremy L. O’bRienWe describe a quantum key distribution protocol based on pairs of entangled qubits that generates a secure key between two partners in an environment of unknown and slowly varying reference frame. A direction of particle delivery is required, but the phases between the computational basis states need not be known or fixed. The protocol can simplify the operation of existing setups and has immediate applications to emerging scenarios such as earth-to-satellite links and the use of integrated photonic waveguides. We compute the asymptotic secret key rate for a two-qubit source, which coincides with the rate of the six-state protocol for white noise. We give the generalization of the protocol to higher-dimensional systems and detail a scheme for physical implementation in the three-dimensional qutrit case.
Journal Article
LMLuca Mazzarella
Luca MazzarellaCLChristopher Lowe
Christopher LoweDLDavid Lowndes
David LowndesSJSiddarth Koduru Joshi
Siddarth Koduru JoshiSGSteve Greenland
Steve GreenlandDODaniel Oi
Daniel Oi +4
Quantum key distribution (QKD) offers future proof security based on fundamental laws of physics. Long-distance QKD spanning regions such as the United Kingdom (UK) may employ a constellation of satellites. Small satellites, CubeSats in particular, in low Earth orbit are a relatively low-cost alternative to traditional, large platforms. They allow the deployment of a large number of spacecrafts, ensuring greater coverage and mitigating some of the risk associated with availability due to cloud cover. We present our mission analysis showing how a constellation comprising 15 low-cost 6U CubeSats can be used to form a secure communication backbone for ground-based and metropolitan networks across the UK. We have estimated the monthly key rates at 43 sites across the UK, incorporating local meteorological data, atmospheric channel modelling and orbital parameters. We have optimized the constellation topology for rapid revisit and thus low-latency key distribution.
Journal Article
MHMatthew Hunt
Matthew Hunt
Mike TaverneJAJoseph Askey
Joseph AskeyAMAndrew May
Andrew MayABArjen van den Berg
Arjen van den BergSLSAM LADAK
SAM LADAK +2
Three-dimensional nanostructured magnetic materials have recently been the topic of intense interest since they provide access to a host of new physical phenomena. Examples include new spin textures that exhibit topological protection, magnetochiral effects and novel ultrafast magnetic phenomena such as the spin-Cherenkov effect. Two-photon lithography is a powerful methodology that is capable of realising 3D polymer nanostructures on the scale of 100 nm. Combining this with postprocessing and deposition methodologies allows 3D magnetic nanostructures of arbitrary geometry to be produced. In this article, the physics of two-photon lithography is first detailed, before reviewing the studies to date that have exploited this fabrication route. The article then moves on to consider how non-linear optical techniques and post-processing solutions can be used to realise structures with a feature size below 100 nm, before comparing two-photon lithography with other direct write methodologies and providing a discussion on future developments.
29 August 2013 in Physical Review Letters
Journal Article
BBBryn Bell
Bryn Bell
SKSrikanth Kannan
Srikanth Kannan
AMAlex McMillan
Alex McMillan
ACAlex S. Clark
Alex S. Clark
WWWilliam J. Wadsworth
William J. WadsworthJohn RarityEntangled photons can be used to make measurements with an accuracy beyond that possible with classical light. While most implementations of quantum metrology have used states made up of a single color of photons, we show that entangled states of two colors can show supersensitivity to optical phase and path length by using a photonic crystal fiber source of photon pairs inside an interferometer. This setup is relatively simple and robust to experimental imperfections. We demonstrate sensitivity beyond the standard quantum limit and show superresolved interference fringes using entangled states of two, four, and six photons.
1 January 2021 in New Journal of Physics
Journal Article
HSHatim Salih
Hatim Salih
Jonte Roderick HanceWMWill McCutcheon
Will McCutcheonTRTerry Rudolph
Terry Rudolph
John RarityWe present a way of directly manipulating an arbitrary qubit, without the exchange of any particles. This includes as an application the exchange-free preparation of an arbitrary quantum state at Alice by a remote classical Bob. As a result, we are able to propose a protocol that allows one party to directly enact, by means of a suitable program, any computation exchange-free on a remote second party's unknown qubit. Further, we show how to use this for the exchange-free control of a universal two-qubit gate, thus opening the possibility of directly enacting any desired algorithm remotely on a programmable quantum circuit.
About Me
Prof. John G. Rarity, FRS, is a Director of QET Labs & Photonics and Quantum in Bristol. He is the Bristol PI and work-package leader on the EPSRC Quantum Technology Hubs in Imaging (EP/T00097X/1) and Communications (EP/T001011/1), and the recipient of several relevant grants (EP/M024458/1, EP/M009033/1, EP/W006685/1). He is a founding father of quantum technologies, publishing pioneering papers in solid-state single-photon detection, quantum interferometry, quantum measurements, and quantum key distribution in fiber and in free space. He has contributed to over 170 refereed publications on nanophotonics and quantum optics (h-index 70, > 18000 citations), including some of the pioneering papers in the field of quantum optics and quantum information. He held an EPSRC-established career fellowship (EP/M024458/1), an ERC advanced grant, and was awarded the IOP Thomas Young Medal in1994, the Descartes Prize in 2004, and the RS Wolfson Research Merit award in 2006---all recognizing his eminence in quantum optics and nanoscience. He was elected as an FRS in 2015.