Vice-Chancellor's Fellows - Profile
Dr Evgeny Chekhovich
Faculty of Science, Department of Physics and Astronomy
2001 - 2007 MSc (with honours) in Semiconductor Physics. M.V. Lomonosov Moscow State University, Department of Physics, Moscow, Russia.
2007 - 2010 PhD in Condensed Matter Physics. Institute of Solid State Physics (ISSP), Chernogolovka, Moscow region, Russia
2010 - 2013 Post-Doctoral Research Associate. Inorganic semiconductors group, Department of Physics and Astronomy, University of Sheffield, UK.
The main motivation behind my research is a challenging task of building a ‘quantum computer’ – a device that uses quantum properties of atomic-size particles, and can outperform any classical computer. Several approaches are considered for realization of a quantum computer. One, particularly attractive option, is to build a ‘quantum microchip’, which will be small and versatile (just like microchips in normal computers), but will operate using the laws of quantum mechanics. The aim of my research is to study the feasibility of using a particular class of materials (semiconductor quantum dots) to build such quantum microcircuit.
Current Research Activity
Quantum dots in III-V semiconductors (e.g. gallium arsenide) have many favourable properties for applications in quantum information processing including strong interaction with light offering excellent optical interfacing, the ability to manipulate at ultrafast speeds and advanced manufacturing technology. The key idea is to use the spin of a single electron trapped in a quantum dot as a two-level quantum system, which acts as a quantum bit (qubit), the basic building block of a quantum computer. However, all atoms of groups III and V have nonzero nuclear magnetic moments. Thus instead of an ideal two-level quantum system, we have a spin of a single electron interacting with an ensemble of ~10000 nuclear spins. This interaction results in decoherence, i.e. decay of the phase information encoded in electron spin. Understanding electron spin decoherence and controlling nuclear spins is crucial for potential applications of quantum dots in quantum computing.
In my research, I use nuclear magnetic resonance (NMR) and electron spin resonance (ESR). These techniques enable direct manipulation of nuclear/electron spins in individual few-nanometer-sized quantum dots using radiofrequency/microwave fields. Magnetic resonance can have a variety of applications, for example, it can be used for structural analysis on a nanometer scale, or for the measurements of interaction strengths between electron and nuclear spins in quantum dots. My most recent work had its aim in probing nuclear spin fluctuations in self-assembled quantum dots: such fluctuations is the main cause of electron spin decoherence. Using pulsed NMR measurements it was shown that nuclear quadrupolar effects induced by elastic strain play an unexpected role: they result in nearly complete suppression of nuclear spin fluctuations. This implies that very long electron coherence is possible, suggesting that III-V self-assembled quantum dots have characteristics orders of magnitude better than previously thought, making them the a promising candidate for integrated semiconductor quantum circuits.
My current research interest is to exploit these outstanding properties of self-assembled dots and demonstrate coherent manipulation of an electron spin quantum dot qubit. Previously such coherent manipulation was achieved only using laser pulses. This had significant drawbacks due to decoherence caused by charge fluctuations induced by optical excitation. My aim is to employ microwave (ESR) pulses instead – this for the first time will enable demonstration of electron spin coherence limited by nuclear spins. Coherence times exceeding few milliseconds are expected – three orders of magnitude longer than in previous optical studies. The ultimate goal of this research is demonstration of a circuit with optical excitation/readout and electrical manipulation of a quantum dot electron spin qubit – a prototype element of a scalable solid-state quantum computer.
- TUoS SURE scheme: 6 week summer studentship project. Total award: ~£1500.
- EPSRC 10 week summer studentship project. Total award: ~£2100.
- Quantum technologies consumables grant for early career researchers (from EPSRC, via University). Total award ~£45k.
- Departmental Scholarship for a fully funded 3 year PhD position. Qingqing Duan will start from Oct-Nov 2014 and will join my ongoing research on nuclear magnetic resonance in semiconductor quantum dots.
Conference Presentations in 2014
- 43rd Jaszowiec International School & Conference on the Physics of Semiconductors, Wisla, Poland, June 2014. I was invited to give a 2 hour lecture to overview basic principles and recent developments in the field of physics of semiconductor quantum dots.
- “Quantum dots 2014” conference (the main international conference in the field of quantum dot physics), Piza, Italy, May 2014. Talk (15 mins): “Suppression of nuclear spin bath fluctuations in self-assembled quantum dots”. I am going to present the most recent results of my work on nuclear spin physics of quantum dots.
- 22nd Symposium “Nanostructures: Physics and Technology”, St. Petersburg, Russia, June 2014. Invited talk (30mins): “Magnetic resonance in self-assembled quantum dots: applications in structural analysis and quantum information technologies”. I was invited to give an overview and present the most recent results of my work on quantum dots using magnetic resonance techniques.
- International Conference on Physics of Semiconductors (ICPS-2014),Austin, USA, August 2014. Largest biannual conference on all aspects of semiconductor physics.
- “Optical Properties of Individual Nanowires and Quantum Dots in High Magnetic Field” workshop in Toulouse, France, September 2014. Talk title: "Optically detected nuclear magnetic resonance in self-assembled quantum dots"
Staff & Students
Currently I am supervising 1 PhD student (Andreas Waeber) who will work until 01/09/2015. His project is nuclear magnetic resonance (NMR) in semiconductor quantum dots. The aim is to study experimentally the effect of quadrupolar interactions on coherent dynamics of nuclear spins in self-assembled quantum dots. The outcomes of these studies are of great importance for quantum-dot-based implementation of quantum information devices.
I am also supervising 1 post-doc researcher (Ata Ulhaq) who is funded by EPSRC Programme Grant (employed until Aug 2016). His current project is development of electron spin resonance techniques on self-assembled semiconductor quantum dots.
Service to Profession
I am taking part in the Management Committee meetings of the ongoing EPSRC Programme Grant “Semiconductor Integrated Quantum Optical Circuits”.
I was co-organiser of a ‘Quantum dot day 2014’ conference which was held on 10 Jan 2014 in Sheffield. There were over 80 participants. My role involved reviewing abstracts, drafting the scientific programme and arranging a venue for the meeting.