What’s on : Lectures

Can beautiful ideas also be useful? – decoding the mysteries of quantum mechanics

14 Mar 2017
Start time
7:30 PM
Tempest Anderson Hall
Dr Jiannis Pachos

Event Information

Can beautiful ideas also be useful? – decoding the mysteries of quantum mechanics

by Dr Jiannis Pachos, Reader in Theoretical Physics, University of Leeds

A lecture for Science Week 2017

Quantum physics fascinates scientists and the public alike.  Sometimes it is like a lens through which reality is viewed more clearly.  At other times we are still at odds with its fundamental properties.  Nevertheless, scientists already successfully employ quantum physics for technological applications, ranging from X-rays, lasers and MRI that transformed modern medicine to semiconductors that revolutionized computers.  Recently, it has been proposed to use the full power of quantum mechanics in the form of a quantum computer.  Can scientists learn how to use something that defies common logic?  Or do we need to understand quantum mechanics in a deeper level before any actual revolution is made in quantum technologies?

Member’s report

This lecture was delayed by a problem with computer technology. Tribute must be paid to the speaker for his patience while waiting for it to be resolved.

The principles of classical and quantum physics seem incompatible – provable laws as against the counterintuitive, spooky and weird. But much technology could not exist without quantum mechanics: from lasers and solar cells to PET, and MRI scanning. The basics of quantum physics – how particles can be measured in either space or time, in one state or another (metal or conductor, for instance) were rehearsed, and too the fundamental philosophical question – do we live in a predeterminate universe or one in which free will exists?

This is bound up with the phenomenon of entanglement – where two particles widely separated apparently influence each other. Measurement of correlations must satisfy Bell inequalities – hidden and non-hidden variables. If free will (however defined) exists, measured states cannot be modelled by classical physics. If the universe is predetermined, the Bell test, of inequalities in the real world, is not disqualified. The conundrum remains unresolved, but experiments have nevertheless produced the possibility of quantum information theory and cryptography.

The analogy of a straight-sided glass and a handled-cup, was used to demonstrate the quantum topology of low-dimensional topology.

Carole Smith