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NANOTECHNOLOGY AND MAGNETIC QUBITS TO IMPLEMENT QUANTUM COMPUTATION

Objective

We propose to work on quantum coherent nanotechnology information devices based on magnetic mesoscopic systems. In particular, we propose to:
i) Investigate the use of such systems as magnetic quantum bits (qubits), hardware elements for coherent quantum memory and computation;
ii) Construct ultra-sensitive microSQUIDs and other sensors - these will enable measurement of the magnetic qubit states, but will clearly have wider magnetic technology applications.

The materials to be investigated as qubits will be both molecular clusters and antiferromagnetic nanoparticles, which will be characterised by using both dc and ac low temperature magnetic techniques and cavity resonance methods. Finally we will implement the coherent manipulation of these magnetic systems and the construction of logic gates and perform magnetic measurements with the developed ultra-sensitive sensors. We propose to work on quantum coherent nanotechnology information devices based on magnetic mesoscopic systems. In particular, we propose to:
i) Investigate the use of such systems as magnetic quantum bits (qubits), hardware elements for coherent quantum memory and computation;
ii) Construct ultra-sensitive microSQUIDs and other sensors - these will enable measurement of the magnetic qubit states, but will clearly have wider magnetic technology applications.

The materials to be investigated as qubits will be both molecular clusters and antiferromagnetic nanoparticles, which will be characterised by using both dc and ac low temperature magnetic techniques and cavity resonance methods. Finally we will implement the coherent manipulation of these magnetic systems and the construction of logic gates and perform magnetic measurements with the developed ultra-sensitive sensors.

OBJECTIVES
The main objective of this work is the first detailed investigation of the prospects of joining nanotechnology devices and magnetic systems for quantum information and storage. Our proposal addresses five key points which evolve from the construction of nanodevices for detection and measurement of mesoscopic spin to the construction of quantum logic gates of one and two magnetic qubits. In between, we aim to search for magnetic mesoscopic systems with two levels which may be mixed at frequencies ranging from MHz to GHz. The decoherence phenomena associated to both intrinsic properties of the molecules/particles and to the interaction of the qubits with the substrate will also be studied with the aim of controlling the life time and, therefore, the operation time of the qubits.

DESCRIPTION OF WORK
The first work to be carried out is the construction of microSQUIDs, microHall probes and other nanodevices which should be capable to detect and measure mesoscopic spin ranging between thousand and few hundred times the Planck's constant. We want to prepare new magnetic molecules and antiferromagnetic particles with controlled values of the total net spin and narrow size distribution. These magnetic systems will be characterised using structural and magnetic methods to determine the values of the spin, aisotropy barrier height, tunneling rate and the quantum coherence splitting. The positioning of both, molecules and particles, will be worked out by using atomic and magnetic force microcopy. The quantum splitting associated to the spin quantum coherence s well as the frequency for the spin precession will be measured in the case of molecules/particles enriched with non nuclear spin isotopes and deposited on selected substrates. The aim is to establish the correlation that exists between the coherence time and the structural and magnetic properties of the clusters/particles. Ths experimental work on decoherence will be supported by theory and simulations. The construction of one- and two-qubits quantum logic gates will be done by arranging the resonances of the qubits to be covered by the range of frequencies of the coupled SQUID. The control of the entanglement between two qubits will be performed by coupling the qubits with a superconducting coil - this generates an interaction Hamiltonian capable of generating entanglement.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

UNIVERSITAD DE BARCELONA
Address
Gran Via Corts Catalanes 585
08007 Barcelona
Spain

Participants (3)

CONSEJO SUPERIOR DE INVESTIGACIONES CIENTÍFICAS
Spain
Address
C(serrano, 117
Madrid
HEWLETT-PACKARD LIMITED
United Kingdom
Address
Cain Road
RG12 1HN Bracknell
NPL MANAGEMENT LIMITED
United Kingdom
Address
National Physical Laboratory, Queens Road
TW11 0LW Teddington, Middlesex