EPSRC Reference: 
EP/P034012/1 
Title: 
Hotelectron quantum optics (HEQO) 
Principal Investigator: 
Emary, Dr C 
Other Investigators: 

Researcher CoInvestigators: 

Project Partners: 

Department: 
Mathematics and Statistics 
Organisation: 
Newcastle University 
Scheme: 
Standard Research 
Starts: 
01 August 2017 
Ends: 
31 July 2020 
Value (£): 
252,481

EPSRC Research Topic Classifications: 
Condensed Matter Physics 
Quantum Optics & Information 

EPSRC Industrial Sector Classifications: 
Electronics 
Communications 

Related Grants: 

Panel History: 
Panel Date  Panel Name  Outcome 
25 Apr 2017

EPSRC Physical Sciences  April 2017

Announced


Summary on Grant Application Form 
Quantum optics is a field of research that employs quantummechanics to investigate phenomena involving light and its interactions with matter. Some of the deepest results in quantum mechanics have been revealed within the framework of quantum optics, and it is also here that some of the most promising quantumtechnology applications, such as quantum communication and cryptography, are being developed.
Workers in solidstate physics have long dreamt of performing their own version of quantum optics in which photons of light are replaced by electrons in a semiconductor. The ultimate goal is to understand and to be able to manipulate the quantum, wavelike properties of the electron, at the same level as we do for photons. From a technological point of view, this is important because electronic components keep getting smaller and, for this to continue, quantum effects will have to be taken into account. Moreover, by harnessing quantum effects we open the doors for new quantum technologies and, from the point of view of integration with conventional technology, semiconductors are ideal for this.
Experimentalists have succeeded in realising a number of nanoelectronic circuits that emulate key photonicquantumoptics experiments, such as the MachZehnder interferometer, that show the wavelike properties of electrons. Whilst these experiments clearly demonstrate the analogy between electron and photon optics, significant differences emerge, most notably because electrons interact with one another whereas photons do not, and because of background electrons that are always present in semiconductors. Unfortunately, in a process known as decoherence, interactions between electrons tend to erase the very signatures of quantum mechanics that we are interested in. This limits the size and complexity of the electron quantum optics setups that we can usefully construct.
We believe that recent experiments on quantumdot charge pumps suggest a way round this problem, and it is the aim of this project to investigate this possibility.
Charge pumps inject electrons onebyone into the semiconductor. These electrons are then confined by a magnetic field in socalled edgechannels, which act as onedimensional ``wires'' that carry the electrons around the circuit. The energy of the electrons emitted by the quantumdot charge pumps we are interested in is particularly high, and this tends to push the electrons out into the edges of the semiconductor and away from the background electrons. This effect can be further enhanced by adding electrical contacts near the edges. The result is that these ''hot'', i.e. highenergy, electrons become well isolated in the edges, well away from all other electrons. This situation then closely resembles the naturallyisolated nature of photons and this, we hypothesise, will drastically reduce the problem of decoherence.
The limits on quantum effects for these hot electrons will therefore not be set by electronelectron interactions, but rather by different mechanisms. In this project we will investigate these mechanisms, isolate the important ones, and devise ways to minimise their negative effects. We will also develop software to simulate realistic hotelectron quantumoptics geometries which will give a detailed understanding of the dynamics of hot electrons in experimentallyrelevant devices.
This work will be conducted in close collaboration with the experimental group of M. Kataoka at the National Physical Laboratory, who are experts in the construction and measurement of chargepump sources. In this way we shall advance the field of electron quantum optics both theoretically and experimentally, and have impact on the mostpromising application of these pumps, that as a reference for highprecision electrical measurements.

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