Abstract
(English)
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The CHIC consortium comprises five groups from 4 different European countries and an American group that will join their forces in Quantum Calculation, Quantum Chemistry, Synthesis, UHV-AFM and UHV-STM, Nano-fabrication, theoretical Near-field Optics and Single Molecule Spectroscopy in order to explore and develop the new concept of Hamiltonian processing, an alternative route mixing molecular nanoelectronics and quantum computing approaches. Scanning Probe Microscopy or Single Molecule Optics envisions it to fabricate a device in which a single molecule is connected to two nano-electrodes and addressed. The tunnel current is used as a generator of non-stationary states. Data encoding is done by single molecule (SPM or optical) manipulation. Detection of the tunnel current channels by near-field optics provides data outputs.
Objectives:
The project objectives are to explore Hamiltonian processing, a new concept of molecular computing. The background idea is to use an electrode-molecule-electrode tunnel junction as a source of non-stationary electronic states and to leave natural intrinsic coherent evolution of the quantum system to process the calculation. The input data are encoded on the Hamiltonian, by modifying locally the molecular electronic structure either by electronic, mechanical or optical manipulation of parts of the molecule. The calculation results are represented by the signature of the inelastic part of the tunnel current in the output part of the molecule and are observed by scanning probe or single molecule spectroscopy. In its final implementation, the Hamiltonian processor will be a device in which a single molecule between two nano-electrodes is addressed by near-field optics.
Work description:
1. A theoretical exploration of the dynamics of a molecular quantum system:
a) The basis of the Hamiltonian parameterisation and its application to the conception of molecules and experimental set-ups;
b) A full theoretical description of a C-NOT gate and of a molecular implementation of the Grover algorithm;
c) The parameters obtained by calculation to design suitable molecules that will be then synthesised and studied first by AFM/STM techniques, then in a coplanar geometry.
2. An investigation of intra-molecular electron transport and mechanics using SPM for imaging, manipulation, conformational switching of molecules on metallic or ultra-thin insulating films:
a) Theory and utilisation of inelastic tunnelling as an activation tool and a non-invasive way of observing tunnel current through its activating consequences;
b) A better characterisation of the tunnel current as a discrete source of non-stationary electronic states;
c) The knowledge acquired in positioning molecules and in inelastic activation used to perform single molecule synthesis giving access to complex architectures at predefined places on a surface. It will require major improvements and modification on UHV AFM and STM microscopes, an optimisation of nano-electrode fabrications and of electricalconnectors.
3. A study of optically addressing and probing single molecules connected to electrodes:
a) determination of useful and detrimental effects of electrodes on the optical response in far-field first at LT;
b) selection of the prominent and more efficient effects (spectral changes, orientation changes of the absorption or emission dipole moments, fluorescence energy transfer or linear and/or quadratic Stark effects), detection of conformational changes at RT;
c) theoretical optimisation of nanometric wave-guides for visible and near-UV light steering the fabrication of these light-guides d) address selectively one molecule.
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