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Quantum Key Distribution at Terahertz Frequencies


Key facts

Type of research degree
Application deadline
Ongoing deadline
Project start date
Friday 1 October 2021
Country eligibility
International (open to all nationalities, including the UK)
Source of funding
Dr Joshua Freeman and Professor Mohsen Razavi
Additional supervisors
Dr Valavanis
School of Electronic and Electrical Engineering
Research groups/institutes
Pollard Institute
<h2 class="heading hide-accessible">Summary</h2>

The possibility of developing quantum computing machines that can break the widely used public-key cryptosystems has required us to look for new solutions to scenarios where long-term data security is needed. Quantum key distribution (QKD) is among the enabling techniques for providing such a level of data security and is being pursued by academic and commercial sectors alike to accelerate its ubiquitous use. Being reliant on few-photon communications, it has generally been perceived that implementing QKD in the optical domain is the most straightforward solution. However restricting this technology to the optical domain could make it more difficult to realise QKD when mobility and wireless access are required. This motivates us to consider using carrier signals at lower frequencies to enable wireless implementations of QKD. Being a few-photon communications system, there is, however, a fundamental barrier to using microwave frequencies for QKD, imposed by the requirement that the carrier photons must have higher, or similar energies, to the thermal background noise. This means that microwave and mm-wave frequencies would require prohibitively low temperature backgrounds. The terahertz regime, on the other hand, offers a regime of operation, where QKD can, in principle, be implemented. This interdisciplinary project has the goal of demonstrating a THz QKD system for the first time. This will be enabled by collaboration between our two well-established theory and experimental groups in quantum communications and THz technologies.

<h2 class="heading hide-accessible">Full description</h2>

<p>THz QKD would have potential applications in secure (inter-)satellite communications. The combination of commercially available satellite launches and the increasing compactness of satellites has driven down the cost of putting satellites into orbit, leading to increasing numbers of satellite launches and planned launches. As the number of satellites and satellite constellations grows, they need communication channels between the satellites that are both high-capacity and secure. Satellite-based QKD is at the moment one of the key focus points for the development of QKD networks.&nbsp;</p> <p>In this project you will implement a special class of QKD protocols known as continuous-variable QKD (CV-QKD). Such protocols rely on generating coherent states with controlled phase and amplitude values of the electric field to encode the information, and homodyne/heterodyne detection at the receiver. Our recent work with THz quantum cascade lasers (QCLs) has enabled us to lock the THz frequency to a near infra-red comb operating around 1550nm. This allows full control over the amplitude and phase of the QCL.&nbsp;</p> <p>As a post graduate researcher working&nbsp;on this project you will be expected to contribute to both theory and experiment. You will work with the existing theoretical team at Leeds to understand how QKD can be implemented at terahertz frequencies and what the fundamental limitations would be. You will also spent at large part of the time working in the state-of-the-art terahertz laboratory at the University of Leeds. Here, the work will focus on using injection-locked quantum cascade lasers to implement QKD protocols and assessing detection capabilities at the few-photon level. Full training will be given on the relavent theoretical and experimental techniques, but an interest in laser physics/engineering and quantum information is desirable.</p> <p>The earliest start date for this project is 1 October 2020.</p>

<h2 class="heading">How to apply</h2>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="">University&#39;s website</a>. Please state clearly in the research information section&nbsp;that the research degree you wish to be considered for is &ldquo;Quantum Key Distribution at Terahertz Frequencies&rdquo; as well as&nbsp;<a href="">Dr Freeman</a>&nbsp;and <a href="">Prof Razavi</a> as your proposed supervisor.</p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>We welcome applications from all suitably-qualified candidates, but UK black and minority ethnic (BME) researchers are currently under-represented in our Postgraduate Research community, and we would therefore particularly encourage applications from UK BME candidates. All scholarships will be awarded on the basis of merit.</em></p>

<h2 class="heading heading--sm">Entry requirements</h2>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

<h2 class="heading heading--sm">English language requirements</h2>

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid.

<h2 class="heading">Funding on offer</h2>

<p>School of Electronic &amp; Electrical Engineering Partial Fee Scholarship to cover partial academic fees of &pound;18,000 for Non-UK applicants.&nbsp; Fee only award for UK applicants.</p>

<h2 class="heading">Contact details</h2>

<p>For further information regarding your application, please contact the Doctoral College Admissions by email: <a href=""></a>, or by telephone: + 44 (0) 113 343 5057</p> <p>For further information regarding the project, please contact Dr Joshua Freeman by email:&nbsp;&nbsp;<a href=""></a></p>

<h3 class="heading heading--sm">Linked research areas</h3>