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Research Fellows Directory

Andrew Green

Dr Andrew Green

Research Fellow


University of St Andrews

Research summary

Condensed matter physics is an area of both techno-

logical and fundamental scienti c importance. Modern

technology is increasingly dependent upon the quantum

behaviour of matter on the smallest scale. The race to

make a quantum computer seeks to use this behaviour

very directly, but quantum mechanics is important in

more familiar technology: transistors, superconductors

and the read heads in hard drives all depend crucially

upon the quantum mechanics of electrons.

Understanding the collective quantum behaviour of

electrons in solids is not only an important driver of

technology, but it also raises fundamental issues with

impact in other areas of science. To take a topical ex-

ample, the explanation of why superconductors hover in

magnetic elds (the Meissner e ect) was provided by the

Anderson-Higgs mechanism | the very same mechanism

that is now thought to provide the origin of mass itself

and which is currently being investigated at FERMILAB

the LHC in CERN.

There is a tremendous symbiosis between theory and

experiment in condensed matter physics. New theoretical

ideas are crucial in guiding experiment in fruitful direc-

tions and puzzling results from experiment are essential

in aiding the development of theory | unraveling these

puzzles can lead to fundamental principles that have an

impact much further a eld.

I study the theory of the collective quantum behaviour

of electrons. I develop mathematical theories predicting

new e ects not yet seen in experiment and work with

experimentalists to understand how these new e ects can

be observed. Together, we determine which experimental

anomalies might be understood within current theories.

Those that cannot provide important guidance and new

directions for theoretical investigation.

Much of my time is spent studying quantum critical

systems. These systems are balanced between the quan-

tum and classical worlds | they obey rules that are

partly like the classical rules of everyday experience and

partly the strange quantum rules of the very smallest

scale. A large variety of materials have electronic be-

haviour that is quantum critical. They have a property

that physicists call universality: their behaviour at low

energy and long distances is largely independent of the

high energy and short distance behaviour. Because of

this, they provide a forum in which we can understand

general features of how classical world emerges from the

quantum behaviour on the microscopic scale without be-

ing distracted by details such as di erences between ma-


Grants awarded

Scheme: University Research Fellowship

Dates: Oct 2001 - Sep 2009

Value: £344,971.77