School of Physics and Astronomy

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Prof Ben Varcoe

Theoretical Physics Group

Contact details

Room: 8.428 
Tel: +44 (0)113 3438290
Email: b.varcoe @


Cavity Quantum Electrodynamics (Cavity QED)
Quantum Key Distribution (QKD)
Continuous Variable Quantum Key Distribution (CVQKD)
Medical Imaging
Quantum Imaging
Magnetocardiogaphy (MCG)

Research interests

Experimental Quantum Information

My principle research area is quantum information science where we are concerned with the physical nature of information and its manipulation. Information is not just a mathematically property, information has to be stored and processed. Storage is always a physical process and processing or manipulating the information requires a physical operation. For this reason information has to be a quantity that obeys the laws of physics. An understanding of the physics of information processing can help us find new ways of manipulating, storing and moving information. It therefore has widespread implications. To cite a specific example in magnetic medical imaging the largest problem faced by researchers was the removal of background noise. The signals, although small, are capable of being detected by a wide range of devices; hence, it is the treatment of the background which is the real problem. By understanding the nature of information we were able to devise a detection array in which the noise problem was dramatically reduced using an error correction mechanism drawn from quantum optics. Moreover we found that rather than reducing the noise, adding quantum noise actually enhances the ability to detect the signal. We also found that the entire signal processing path needs to be considered in the design of the apparatus, it is not sufficient to consider (or optimise) each element in isolation.

Quantum Communication

Experimental quantum communication at Leeds is working with a spinout company, Cryptographiq Limited, and development partners Airbus Defence and Space, and L3-TRL to develop new and novel communications technologies that will provide future proof cryptographic systems that are based on quantum information principles.

We are also working with the quantum communication hub to deliver a microwave quantum key distribution system. The quantum communications hub consortium has bid successfully for Government funding to be one of four hubs in the EPSRC's new £155m National Network of Quantum Technology Hubs announced today by Greg Clark, Minister of State for Universities, Science and Cities. The new hubs are the centre-piece of the £270 million investment in the UK National Quantum Technologies Programme announced by the Chancellor in the 2013 Autumn Statement.

Quantum Imaging

Coronary artery disease (CAD) represents a significant challenge to both cardiologists and emergency medicine specialists. They must diagnose both symptomatic and asymptomatic patients with multiple cardiovascular risk factors, as well as patients presenting with acute chest pain without any clinical signs. As of 2012, CAD was the most common cause of death globally and a major cause of hospital admissions. Acute coronary syndrome (ACS) refers to a spectrum of cardiac conditions ranging from unstable angina to myocardial infarction (MI) that are caused by a sudden reduction in blood flow to the heart. The most common symptom of ACS is chest pain. Distinguishing between ACS and other causes of chest pain is a huge challenge for cardiologists.

Medical Magnetocardiography (MCG), primarily using Superconducting Quantum Interference Devices (SQUIDs), has been used in clinical research for over 50 years, but its widespread adoption has been restricted by high costs (>1 million), the need for highly controlled environments and liquid helium cooling, as well as specialist staff. The University of Leeds has designed a portable magnetometer to enable MCG to be easily employed, at a reduced cost compared with SQUID MCG, in hospital accident and emergency departments or other acute settings.

The Magnetometer Model 1.0 (V1) is a prototype, which was developed using academic research funding at the University of Leeds. This is currently being used in a clinical study, which is also funded by a grant to the University. Quantum Imaging (QI) Ltd is developing Magnetometer Model 2.0 (V2), which can be easily deployed in an acute medical setting. Earlier this year Quantum Imaging Ltd was spun out from the University of Leeds to commercialise the technology.

The QI Magnetometer will identify healthy (non-cardiac) patients and as such addresses two significant unmet healthcare and clinical needs in cardiology. The first is to rule out CAD, including stable and unstable angina and MI, sooner in patients presenting with chest pain. Currently, only 13% of patients with chest pain are discharged within 4 hours of arrival; and around 75% of patients with chest pain of a non-cardiac origin are inappropriately triaged through the chest pain pathway. The second is to prevent inappropriate discharge of patients with a missed MI; around 2%-4% of patients with evolving MI are discharged from the emergency department because of normal electrocardiogram (ECG) findings.

This represents a step change in clinical capability. It will revolutionise the rapid diagnosis of CAD, filtering out those who do not need to be in the care a dedicated cardiology team quickly and efficiently. It will allow clinical teams to focus their effort on those patients who are most in need and reduce waiting times. This will lead to significant cost savings and improved health care.