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Universities and Science Minister, Jo Johnson, visits NQIT Hub




The Universities and Science Minister, Jo Johnson, visited Oxford, where he saw first-hand the world-leading research being carried out at the University.

Mr Johnson was shown laboratory and workshop facilities, and met doctoral students, in the University’s Networked Quantum Information Technologies (NQIT) Hub and Mobile Robotics Group.

The NQIT Directors spoke with Mr Johnson about the UK National Quantum Technology Programme and why quantum technology is such an exciting area for research and technology development. He then was given a tour of our NQIT lab in the Physics Department where Vera Schafer, a doctoral student, and Dr Ben Metcalf, a post-doctoral researcher, explained how their research into ion traps and photonics provide the core hardware for NQIT’s Q20:20 quantum computer.

During his visit, Mr Johnson announced new Government funding to support DPhil students in engineering and physical sciences, as well as significant funding geared towards boosting the UK’s research into quantum technologies. This funding is a national investment in science totalling £204 million – £167 million for Doctoral Training Partnerships involving 40 universities and £37 million as part of the UK’s National Quantum Technologies Programme.

Mr Johnson said: ‘We are committed to securing the UK’s position as a world leader in science and innovation. The Government is ensuring major new discoveries happen here, such as the creation of super-powerful quantum computers which scientists are working on in Oxford. This new funding builds on our protection for science spending by supporting research in our world-leading universities and helping to train the science leaders of tomorrow.’

Professor Louise Richardson, Vice-Chancellor of the University of Oxford, said: ‘Quantum technologies promise to revolutionise the way we live our lives. At Oxford we stand at the forefront of this revolution through our world-class research and training programmes. It is a pleasure to welcome the Minister to Oxford to announce support for this key research area, as well as significant funding for doctoral places in engineering and physical sciences that will help us continue to train the leading scientists of the future.’

Professor Ian Walmsley, Hooke Professor of Experimental Physics, NQIT Hub Director, and Pro-Vice-Chancellor (Research and Innovation) at the University of Oxford, said: ‘Quantum technologies will deliver novel sensors, secure communications and advanced computing that are impossible with conventional technologies. This radical reconnection of the information processing landscape will also deliver benefits to society, and to the UK economy, through highly skilled and knowledgeable graduate students who work at the cutting edge of the field and are able to translate quantum science into applications through new technologies.’

Read more about Jo Johnson’s visit to Oxford:

All photos are by John Cairns.


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Hub job opportunity!




University of Cambridge

The Department of Engineering, University of Cambridge, seeks to appoint a Research Associate to work on Quantum Communications as part of the Quantum Communications Hub, until 30 November 2022, extendable for another 2 years.

The post holder will be located in the Electrical Engineering Building on the West Cambridge Site, Cambridge, UK.

The key responsibilities and duties are to maintain the network and introduce new systems for trial. This will involve design, construction and assessment of sub-systems. Examples of tests are the hybrid Continuous Variable (CV) QKD system, the new Quantum Alarm, and options for carrying out signal processing using CV techniques. Preference will be given to candidates with demonstrated quantum or photonic communications experimental aptitude in relevant areas of research and an ability to work within a team. Experience of DSP/FPGA programming would be an advantage.

The qualifications required to perform the role are to have obtained a PhD in Electronic Engineering, Physics, Applied Maths, Computer Science, or a related discipline. A good publication record would be an advantage.

Salary Ranges: Research Associate: £32,816 – £40,322

Fixed-term: The funds for this post are available until 30 November 2022 in the first instance.

For more information regarding this position follow this link.


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Quantum Algorithms for Simulating the Lattice Schwinger Model




Alexander F. Shaw1,5, Pavel Lougovski1, Jesse R. Stryker2, and Nathan Wiebe3,4

1Quantum Information Science Group, Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, U.S.A.
2Institute for Nuclear Theory, University of Washington, Seattle, WA 98195-1550, U.S.A.
3Department of Physics, University of Washington, Seattle, WA 98195, U.S.A.
4Pacific Northwest National Laboratory, Richland, WA 99354, U.S.A.
5Department of Physics, University of Maryland, College Park, Maryland 20742, U.S.A.

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The Schwinger model (quantum electrodynamics in 1+1 dimensions) is a testbed for the study of quantum gauge field theories. We give scalable, explicit digital quantum algorithms to simulate the lattice Schwinger model in both NISQ and fault-tolerant settings. In particular, we perform a tight analysis of low-order Trotter formula simulations of the Schwinger model, using recently derived commutator bounds, and give upper bounds on the resources needed for simulations in both scenarios. In lattice units, we find a Schwinger model on $N/2$ physical sites with coupling constant $x^{-1/2}$ and electric field cutoff $x^{-1/2}Lambda$ can be simulated on a quantum computer for time $2xT$ using a number of $T$-gates or CNOTs in $widetilde{O}( N^{3/2} T^{3/2} sqrt{x} Lambda )$ for fixed operator error. This scaling with the truncation $Lambda$ is better than that expected from algorithms such as qubitization or QDRIFT. Furthermore, we give scalable measurement schemes and algorithms to estimate observables which we cost in both the NISQ and fault-tolerant settings by assuming a simple target observable–the mean pair density. Finally, we bound the root-mean-square error in estimating this observable via simulation as a function of the diamond distance between the ideal and actual CNOT channels. This work provides a rigorous analysis of simulating the Schwinger model, while also providing benchmarks against which subsequent simulation algorithms can be tested.

► BibTeX data

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Cited by

[1] Indrakshi Raychowdhury and Jesse R. Stryker, “Solving Gauss’s Law on Digital Quantum Computers with Loop-String-Hadron Digitization”, arXiv:1812.07554.

[2] Christopher David White, ChunJun Cao, and Brian Swingle, “Conformal field theories are magical”, arXiv:2007.01303.

[3] Anthony Ciavarella, “An Algorithm for Quantum Computation of Particle Decays”, arXiv:2007.04447.

[4] Minh C. Tran, Yuan Su, Daniel Carney, and Jacob M. Taylor, “Faster Digital Quantum Simulation by Symmetry Protection”, arXiv:2006.16248.

The above citations are from SAO/NASA ADS (last updated successfully 2020-08-12 00:44:15). The list may be incomplete as not all publishers provide suitable and complete citation data.

On Crossref’s cited-by service no data on citing works was found (last attempt 2020-08-12 00:44:14).


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Mapping graph state orbits under local complementation




Jeremy C. Adcock1, Sam Morley-Short1, Axel Dahlberg2, and Joshua W. Silverstone1

1Quantum Engineering Technology (QET) Labs, H. H. Wills Physics Laboratory & Department of Electrical & Electronic Engineering, University of Bristol, Merchant Venturers Building, Woodland Road, Bristol BS8 1UB, UK
2QuTech – TU Delft, Lorentzweg 1, 2628CJ Delft, The Netherlands

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Graph states, and the entanglement they posses, are central to modern quantum computing and communications architectures. Local complementation – the graph operation that links all local-Clifford equivalent graph states – allows us to classify all stabiliser states by their entanglement. Here, we study the structure of the orbits generated by local complementation, mapping them up to 9 qubits and revealing a rich hidden structure. We provide programs to compute these orbits, along with our data for each of the $587$ orbits up to $9$ qubits and a means to visualise them. We find direct links between the connectivity of certain orbits with the entanglement properties of their component graph states. Furthermore, we observe the correlations between graph-theoretical orbit properties, such as diameter and colourability, with Schmidt measure and preparation complexity and suggest potential applications. It is well known that graph theory and quantum entanglement have strong interplay – our exploration deepens this relationship, providing new tools with which to probe the nature of entanglement.

Graph states are ubiquitous representations of entanglement in quantum information science, and classify the most studied set of quantum states—clifford states—by the entanglement they possess.

However, many graph states are locally equivalent to one another, that is, they possess the same type of entanglement. Graph states which are locally equivalent can be transformed into one another by successive applications of the graph operation local complementation (example shown above). Using this operation, we can analyse only graph structure of the state, which is much simpler than analysing the exponentially large quantum state vector. This equivalence of graph states has been studied previously, with all graph states up to 12 qubits classified.

However, local complementation gives us more than sets of locally equivalent graphs: it also gives us an orbit (example shown above) which tells us how different graphs are related via local complementation. In this work we study these orbits, and relate their properties to properties of the entangled quantum states they contain. We find that orbit properties, such as colourability, correlate with entanglement properties, such as schmidt measure, and discuss applications of local complementation in quantum technology.

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► References

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