At Sussex, you learn from experts working at the forefront of physics. This means you study modules based on the latest research, whilst exploring the fundamental laws of physics. In the research placement programme, you will have the opportunity to directly experience world-leading physics research through paid placements in active research groups during the summer holidays. This unique experience will give you a significant advantage when you apply for jobs, either in academia or in industry.

Circuit Quantum Electrodynamics with a single trapped electron

Faculty advisor: Jose Verdu Galiana

The aim of this project is the development of a novel trapping technology for capturing a single electron which will become one building block of future quantum circuits. For that purpose a superconducting planar microwave cavity will be used. The experimental set-up consists of an ultra-low vibration cryostat, achieving temperatures as low as 2.2 K. The project is about to start and represents a unique opportunity to learn how to build a modern experiment in quantum electrodynamics from scratch.

Keywords: Microwave Engineering, Superconductivity, RF-Electronics, Computer Control with Lab-View, Planar Penning trap technology, ultra precise  measurement of fundamental constants, low dimensional electron gases, Quantum Hall effect, circuit-QED.

Ion Quantum Technology

Faculty advisor: Winfried Hensinger

Quantum theory can have powerful applications due to the possibility of implementing new quantum technologies such as the quantum computer. While such a device could have very important commercial and national security applications due to the existence of quantum factoring algorithms, its existence would revolutionize modern day science by allowing true quantum simulations of systems that may be modelled classically only insufficiently due to an in-principle limitation of current computer technology. Recent developments in ion trapping technology show that it should be possible to build a quantum computer with trapped ions. In the Ion Quantum Technology group at Sussex, we are in the process to build an elementary quantum computer, an effort that will be based in Sussex but include links to nanofabrication facilities, ion trapping groups and theorists around the world. More information, including a virtual lab tour, can be found on our website.

1. Laser cooling of ytterbium ions

Trapping single atoms is being described as one of the most demanding experiments in atomic physics. This project includes experimental work in trapping and cooling single ions towards the realization of an ion trap quantum computer. You will learn about laser cooling of ytterbium ions. Furthermore, you will study ways how to cool the ions to the quantum mechanical ground state. This project includes both theoretical and experimental parts. You will learn how to align lasers onto the ion trap, operation of a laser locking scheme, and the handling of a complicated imaging system as well as studying the theoretical foundations of how to manipulate ions using lasers. Your work should leads towards the experimental realisation of ground state cooling with trapped ions.

2. Lasers and laser locking for trapping ytterbium ions

Trapping ytterbium ions requires a number of lasers all operating at the required frequency to perform cooling and trapping of ytterbium ions. As part of this project you learn about the lasers required and construct a new laser that will be used for the ion trapping experiments. You will also learn about laser locking and build a laser locking scheme that allows for much higher laser stability. This is a prerequisite for efficient entanglement and detection capabilities.

3. Advanced ion chips

For large scale quantum computing to occur large scale ion trap arrays need to be designed that allow optimal storage, shuttling and entanglement operations to be performed. The arrays are constructed within an integrated microchip. In this project you will study how to add advanced features to ion chips such as digital signal processing, on-chip cavities, fibre connects along with on-chip resistors and capacitors. In addition, you will devise recipes for the application of microwaves on the chip and the implementation of magnetic field gradients. You will identify important issues in nanofabrication of ion traps and address such challenges with advances in condensed matter physics.

4. Quantum Hybrid Systems

This project focuses on the demonstration of novel routes towards scaling up physical devices for quantum computation and quantum information processing. Development of a scalable technology will be pursued by first advancing arrays of micro-fabricated ion traps (atom-optical devices) and arrays of superconducting qubits coupled to microwave resonators (solid-state devices). Combining these two technologies can yield a scalable basis for universal quantum computation and processing of quantum information. The superconducting qubits are exploited for fast and scalable computational tasks and trapped ions are exploited for storage and processing of information with long coherence times.

5. Shuttling trapped ions inside arrays

In our group we develop advanced ion trap arrays on a chip. In order to transport ions through such an array of electrodes the motion of the ion has to be carefully controlled. This project investigates how ions can be carefully shuttled in such an ion trap array without changing their motional quantum state. You will investigate optimal ways to transport individual ions and develop voltage sequences that are applied to multiple electrodes in order to move ions along a line, transport them through a junction or separate ions that are part of an ion string.

6. Entanglement creation

Quantum technology, particularly quantum computing relies on the ability to entangle ions. Entanglement has been referred by Einstein as “spooky” and is one of the most counterintuitive predictions of quantum physics. At Sussex we work on a scalable method to create entanglement using microwaves. This project may involve some theory, programming and experimental work. You will also evaluate how to increase gate fidelities in order to reduce error rates within quantum computing operations.

7. Quantum simulations with trapped ions

Richard Feynman pioneered the idea that instead of trying to simulate quantum systems with classical computers, it is much more efficient to use a quantum system that can be controlled in the lab to simulate another quantum system one would like to understand. There is a vast range of possible quantum simulations that can be performed using trapped ions from all areas of physics, including effects of Einstein’s theory of special relativity, the Kibble-Zurek mechanism, particle creation moments after the big bang and complex many-body phenomena such as quantum biology and quantum chemistry. The aim of this project is to analyze and further develop theoretical proposals for quantum simulations and carry out the corresponding experiments using trapped ions at Sussex.

8. Communicating quantum technology

A famous quantum physicist once proclaimed that the only physicists who understand quantum physics are the ones who know that they don’t understand it. Within this project you will analyze the factors that lead to the difficulty in obtaining an intuitive understanding of quantum physics. Once these factors become clear, you will devise strategies to circumvent such problems and create a strategy to communicate quantum technology research to a number of different target groups such as the general public, A-level students and undergraduate physics students. You will then create appropriate materials such as websites, simulations, applets, handouts and hand-on demonstrations in order effectively communicate quantum technology research. You will also measure the efficiency of the created strategy and materials by analyzing its effect on various target groups. Experience in making websites and interactive simulations would be very useful.

Quantum systems from confined cold atoms

Faculty advisor: Barry Garraway

Quantum physics offers exciting routes to new devices such as high precision interferometers, motion sensors, realistic designs for large-scale quantum simulations, and quantum logic modules leading to quantum information processors. This project involves theoretical studies of new ways to confine very small numbers of atoms to realise these kinds of devices. You will start with understanding the literature and with simulations of classical models of atom-chip and related systems which confine the atoms using electromagnetic fields. We will also undertake a quantum analysis and new designs will be made for structures that trap atoms about micro-fabricated surfaces.

In this project you will be involved in computer simulations, visualisation and with theoretical models.

Single-ion cavity QED

Faculty advisor: Matthias Keller

The interaction of light and matter is one of the most important processes in physics. In our experiment we investigate this interaction at the smallest possible level, involving only a single atom and a single photon. The atom is ionised and stored in a device called a radio-frequency ion trap, using alternating electric fields to keep it in place for many hours. The photon is more volatile, but we can keep it in the apparatus sufficiently long by using two mirrors with ultra-high reflectivity, forming a cavity which repeatedly bounces the photon back to the ion before it finally escapes.

The behaviour of this set-up is determined by the laws of quantum mechanics, which are vastly different from the physics encountered in everyday life. For example, the ion and photon can reside in two distinct states simultaneously. After having interacted, their states may be strongly entangled, no matter how far they are separated. These strange properties can be exploited to devise a quantum computer which is orders of magnitude more powerful than its classical counterpart. We are exploring ways to link quantum computers by means of photons, which we must generate with unprecedented control. The final goal is to lay the foundation for the quantum internet, in which quantum states are exchanged reliably over long distances.

During the research placement course the student will be involved in a range of research tasks in the laboratory, including work with diode lasers, to excite and manipulate the ion, electronics for controlling the experiment and ultra-high vacuum equipment to provide a suitable environment for exploring single ions and photons.

Single Molecules Under Control: Laser stabilisation for the manipulation of single molecular ions

Faculty advisor: Matthias Keller

Molecular ions are versatile tools with applications reaching from the investigation of ultra-cold chemical reactions and quantum information processing to high resolution spectroscopy and the test of the time-dependence of fundamental constants.

While the internal states of atoms are completely determined by their electronic configurations, molecules exhibit a more complex level structure. The nuclei of the bound atoms can undergo rotational and vibrational motion with respect to their centre of gravity. Accordingly, for any electronic state, the molecule can be in a large number of rotational and vibrational states. As the excited states of the molecules can spontaneously decay through various channels to different states, there are no closed transitions in the system. Therefore, it is not possible to pursue direct laser cooling or manipulation and detection of molecular states. However, by trapping molecular ions alongside atomic ions in a RF-trap, the molecules are coupled to the atomic species through their common motion. This can be exploited to cool and detect the state of the molecule indirectly through the atomic ion.

Your task on this experiment at the frontiers of modern atomic physics is to set up and stabilise lasers. This includes designing, building and testing of electronic circuits and the set up of optical systems.

Transferable skills: electronic development; handling and adjustment of optical instruments.

Restrictions: none.

Computational quantum mechanics

Faculty advisor: Diego Porras

Some problems in quantum mechanics can be explored with modest computational effort. In particular, the effect of disorder and noise in the propogation of a particle can be simulated by solving systems of differential equations. Also, the propogation of a particle in the presence of a magnetic field can be addressed by solving tight-binding models describing two or three dimensional lattices. In this project we will focus on the emergence of phenomena like Anderson localization and the formation of topological states. We will also find analytical approximations to account for the observed phenomena. Other techniques may include Monte Carlo calculations and the study of stochastic differential equations.

The student will learn to program in MATLAB, something that requires very basic programming skills. Although the project will involve some computational work, the student will also learn theoretical approaches to get analytical descriptions of quantum phenomena. The research placement will involve, at some stage, to deliver graphics and animations that can be used to present the results to other students and researchers. The student must have a strong vocation for theoretical physics, and be willing to learn theoretical physics beyond the standard content of the physics degree.

Restrictions: This is for theory students or students with a strong vocation for theoretical physics.

Setup of a photonic characterization bench using ultrafast optical sources

Faculty advisor: Marco Peccianti

In 1872 Leland Stanford, a businessman and former governor of California, challenged Edward James Muybridge, an English photographer, with the specific purpose of demonstrating that, when a horse is running or trotting, in a brief moment all four hooves leave the ground at the same time. At the time this subject was popularly debated as the human eye could not break down the action. Using a new shutter design he had developed which operated in as little as 1/1000th of a second (millisecond), Muybridge produced a now famous detailed sequence of the horse run.

What do we have to do to resolve extremely fast events that occur in the timescale of picoseconds (1/1000000000000th of a second) or below, like the movement of an electron or the propogation of an electromagnetic wave? A state-of-the-art-laser, the Titanium Sapphire mode-locked laser, emits trains of very intense ultra-short optical pulses. Those pulses can be used as an ultrafast "flashlight" capable of freezing actions occuring in an extremely short time-scale (below 0.1 picoseconds). This research project will focus on the establishment of such a technology within the Terahertz Imaging Advances Lab (THEIA) of the School of Mathematical and Physical Sciences. The goal of the research activity is to establish an optical setup to characterize different ultrafast phenomena using an ultrafast optical source.

The students are expected to undertake a number of experimental activities that will include specific scientific training from a senior scientist in managing and handling laser sources generating ultrashort pulses. The students are expected to be involved fully in the building and commissioning of a significant part of the characterization system (which could involve, but is not restricted to, some computational tasks).

Using quantum physics to improve measurement technology

Faculty advisor: Jacob Dunningham

One of the most exciting new potential technologies to emerge from quantum physics is the ability to measure physical phenomena with unprecedented precision. This could allow us to subject scientific theories to higher levels of scrutiny and lead to a range of new industrial applications. Current sensors rely on conventional (classical) physics. However, by using a fully quantum approach it is possible to achieve much greater sensitivities to phenomena such as magnetic, electric or gravitational fields or rotations. Quantum sensing could therefore be applied to detecting and identifying remote objects or (in the case of rotations) improving the precision of gyroscopes for navigation and stabilisation devices. While the feasibility of these ideas has been demonstrated in principle, the key problem is making them practical. The quantum states required for many schemes are difficult to engineer and fragile to noise which is inevitably present in any real-world situation. In this project we will study the principles of quantum enhanced sensing and develop schemes that overcome these problems. The key aim will be to identify a way of achieveing a sensitivity that surpasses anything possible in classical physics even when the effects of noise are accounted for.

The project will involve numerical calculations and theory.

Listen to Tom Whitmore, MPhys Physics (Research Placement) student talking about his summer 2016 Research Placement

Listen to Ross Callaghan, MPhys Physics (Research Placement) student talking about his summer 2014 Research Placement