Blog Posts

Spinning out of Equilibrium

September 22, 2020

When ice melts in a drink or a cup of coffee cools down to room temperature, energy is exchanged between the drink and its environment until they reach a thermal equilibrium. This is true for any physical system, from regular liquids like drinks through to complex quantum mechanical systems like trapped ions or ultracold atomic gases. When a system connected to its environment is subject to some form of perturbation, it will always eventually return back to its equilibrium state: think of a Newton’s cradle, for example, which you can ‘perturb’ by setting it in motion, but which will always eventually return to its equilibrium (static) state as its kinetic energy is slowly dissipated to its environment through friction (heat) and sound.

Many-Body Localisation: A Flow Equation Approach

March 23, 2018

When asked what are the big outstanding challenges in modern physics, a number of things may spring to mind. Perhaps the search for a theory of quantum gravity, that elusive unification of relativity with quantum mechanics, or maybe the LHC’s continued search for physics beyond the Standard Model. By comparison, the question of how impurities in quantum materials can affect their properties seems quaintly pedestrian, but it turns out to be every bit as fundamental a question as its ostensibly deeper cosmological cousins.

Research Update: Many-Body Localisation in 2 Dimensions

October 31, 2017

It’s been a while since I last blogged – again – but today I’m back with a quick update on some research progress. A while back, I posted about a new preprint that we’d just uploaded to arXiv, the repository where physicists routinely post drafts of their new papers before they go through peer review and are considered for publication in a ‘proper’ journal. The paper was about some new work on many-body localisation (MBL) where we developed a new technique to look at the time-dependence of MBL systems.

Bring Me The Event Horizon

September 4, 2017

This feature-length article was originally written for the September-October 2017 issue of Popular Astronomy magazine. Through a modest 4-inch telescope on a clear night, you might be able to see the rings of Saturn and the moons of Jupiter. Through a meter-wide telescope, you might just be able to make out the characteristic blips in starlight that signify the presence of extrasolar planets. But to see the distant supermassive black hole in the heart of our galaxy, you’d need something much, much bigger – in fact, you’d need a telescope the size of a planet.

Flow Equations for MBL

July 24, 2017

This is just a short post to advertise our new pre-print that appeared on arXiv this morning: “Time Evolution in Many-Body Localized Phases with the Flow Equation Approach”. I’ll save the full write-up of it until the paper is properly published: for my non-academic readers, let me just be clear up front that this is a pre-print, which means that it hasn’t yet been published by a journal or gone through the peer-review process.

Seeing Into the Quantum Heart of Matter

July 3, 2017

When I moved to St Andrews as a long-haired, clean-shaven 17-year-old, it wasn’t to embark on a career as a quantum theorist – my degree was originally to be in astrophysics. For two years, I was an astrophysics student, before eventually ditching space in favour of quantum physics. There were two main reasons for this. The first is that quantum mechanics is mindblowing, and as soon as I saw it I knew I wanted to study it more.

When Randomness Meets Subatomic Precision

June 8, 2017

In 1960, Theodore Maiman and co-workers created the world’s first laser. Working on the principle of Light Amplification by Stimulated Emission of Radiation, the beam produced by a laser is unique in that all the photons in the beam have both the same wavelength and the same phase. Because of this innocuous-sounding property, the humble laser went on to change the world. Top: waves with the same phase add together to make a bigger wave.

My Current Research Topic: Many-Body Localisation

May 29, 2017

It’s always exciting in science when a surprise comes along and something you thought you knew turns out to be wrong. In the last decade, spurred on by recent experimental advances, condensed matter theorists have turned back to an old problem with renewed enthusiasm, and have discovered an enigmatic phase of matter that behaves unlike anything else we know of. The behaviour in question is called many-body localisation and it’s the topic of my current research.

The Role of Disorder Under the (Quantum) Microscope

November 14, 2016

One of the biggest problems with researching quantum mechanics is that it’s often hard to visualise what we’re dealing with. Are we talking particles, or are we talking waves? Or are we talking about abstract excitations of a quantum field, somewhere between neither and both? For the most part, we focus on calculating properties that can be experimentally measured and we don’t worry too much about what really lies behind quantum mechanics, since we’ve currently no way to test that.

The Best Defence Is...

September 19, 2016

Today is exactly one month since one of the best days of my PhD: the viva. Having had a month to come to terms with real life after 8 years of being a student, I wanted to write something about my viva experience. This isn’t a how-to or a guide or anything of the sort – it’s just a few words on my own viva and how it went.