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Natalia Ares

Dr Natalia Ares
TWCF Fellow

Department of Materials
University of Oxford
16 Parks Road
Oxford OX1 3PH
UK

Tel: +44 1865 273719 (Room 195.20.09)
Tel: +44 1865 273777 (reception)
Fax: +44 1865 273789 (general fax)


Projects Available

Efficient quantum device tuning using machine learning
Dr N. Ares / Professor G. A. D. Briggs

Fault-tolerant quantum computers require hundreds to millions of physical qubits to be operated with high fidelity. Inevitable hardware imperfections must be tuned away through iterative interplay of characterization, simulation, and parameter refinement, with each data point informing the decision of what to measure next. The technology is only scalable if this task can be efficiently automated. Recent progress in machine learning, currently one of the most rapidly developing fields of computing, makes it possible to automate the entire process. This project will apply these new techniques experimentally, working with leaders in machine learning.

The objective is to achieve automated tuning of semiconductor qubits encoded in gate-defined quantum dots. These qubits are an ideal testbed because the physics is known and the device parameters are conveniently optimized by gate voltages. Nonetheless, tuning a simple device by hand takes days to weeks, which is clearly not scalable.  We expect this machine learning approach to enable the tuning of large quantum circuits.

 

Also see homepages: Natalia Ares Andrew Briggs

Thermodynamics at the nanoscale
Dr N. Ares / Professor G. A. D. Briggs

Experimental techniques for manipulating small fluctuating systems, such as qubits, are now mature and a great effort for developing quantum technologies is in place.  These quantum devices are systems that evolve, fluctuate and couple to each other and to the environment. As larger quantum circuits are pushed forward, studying the thermodynamics of small systems becomes crucial.  With an experimentally grounded understanding of thermodynamics at the nanoscale, it will be possible to refine future quantum devices through their fully informed design. There is also the possibility of unique behaviours that would open the way for new technologies, such as new refrigeration and sensing techniques, as well as innovative means of storing energy and powering engines. 

To constitute the simplest and most paradigmatic thermodynamic system, we require a system coupled to a heat bath and a battery. In the proposed platform, the system is a two-level quantum system coupled to a nanomechanical resonator, a vibrating carbon nanotube. The resonator stores and provides mechanical work, playing the role of a battery. A cavity will give access to time-resolved measurements of the “battery” and, therefore, will enable direct measurements of the work exchanges in a nanoscale device.

 

Also see homepages: Natalia Ares Andrew Briggs

Bench-top experimental tests of gravitation in quantum systems
Dr N. Ares / Professor G. A. D. Briggs

The territory where quantum mechanics has to be reconciled with gravitation is still experimentally unexplored. Gravitational effects in quantum systems are typically small, making laboratory-scale experiments extremely challenging. Advances in mechanical resonators at the micro-scale and cryogenic temperatures are beginning to bring such experiments within reach. We plan to evaluate the feasibility of bench-top experiments based on two micromechanical oscillators to explore the effect of gravity in quantum systems. 

Heating of mechanical resonators is expected from gravitational decoherence. To determine whether this heating effect can be measured, we will build the world’s most sensitive calorimeter based on an optomechanical system at cryogenic temperatures. The optomechanical system will consist of a mechanical oscillator inside a 3D microwave cavity, whose interaction will allow for measurement of the mechanical oscillator’s temperature. The microwave cavity is fabricated from an aluminium block and the mechanical resonators are commercially available silicon nitride membranes with excellent mechanical properties. 

This is an ambitious project with the goal of elucidating whether quantum gravitational effects can arise in table-top experiments, opening up the possibility for a whole new direction for the quest of quantum gravitational effects. 

Also see homepages: Natalia Ares Andrew Briggs

Also see a full listing of New projects available within the Department of Materials.