Entanglement and New Quantum Phenomena in Semiconductor Nanostructures

The project will develop and extend our recent experimental discovery that electron-electron repulsion can
break a single row of confined carriers into two or more separate rows, this is the start of a Wigner Lattice in
which the mutual repulsion of the electrons determines how they organise in space. The separate lines of the
zig-zag are entangled and give rise a new fractional conductance, which comprises novel, highly interacting,
fractional state. This phenomenon is the long sought non-magnetic equivalent of the Fractional Quantum Hall
Effect. Theory has established that the fractions arise due to the entanglement of two rows of electrons which
can be manipulated by varying their mutual separation.The new fractions will be studied as a function of
electric and magnetic fields which alter the wavefunctions, in particular the formation of the fractional state in
quantum dots of differing geometries will be explored and a read-out mechanism established.
Electron focussing in which a current is injected into a 2D region and then focused by a magnetic field allows
an imaging of the ground state wave function which changes as electrons strongly interact. We have recently
shown that this method allows observation of the transtion from single to double rows and it will be a valuable
diagnostic tool for the formation of the Wigner lattice. The technique can also be used to determine the spin
polarisation of the separate rows of the lattice.
The physics of the process will be explored and a Quantum Computation scheme developed based around the
entanglement of the electrons as the Wigner Lattice forms. The experiments will use the group's very low
temperature facilities and will involve device fabrication in the LCN Clean Room and collaboration with theorists
in the UK and abroad.