14 research outputs found
Cluster of Dipolar Coupled Spins as a Quantum Memory Storage
Spin dynamics of a cluster of coupled spins 1/2 can be manipulated to store
and process a large amount of information. A new type of dynamic response makes
it possible to excite coherent long-living signals, which can be used for
exchanging information with a mesoscopic quantum system. An experimental
demonstration is given for a system of 19 proton spins of a liquid crystal
molecule.Comment: 5 pages, 1 figur
Use of Quadrupolar Nuclei for Quantum Information processing by Nuclear Magnetic Resonance: Implementation of a Quantum Algorithm
Physical implementation of Quantum Information Processing (QIP) by
liquid-state Nuclear Magnetic Resonance (NMR), using weakly coupled spin-1/2
nuclei of a molecule, is well established. Nuclei with spin1/2 oriented in
liquid crystalline matrices is another possibility. Such systems have multiple
qubits per nuclei and large quadrupolar couplings resulting in well separated
lines in the spectrum. So far, creation of pseudopure states and logic gates
have been demonstrated in such systems using transition selective
radio-frequency pulses. In this paper we report two novel developments. First,
we implement a quantum algorithm which needs coherent superposition of states.
Second, we use evolution under quadrupolar coupling to implement multi qubit
gates. We implement Deutsch-Jozsa algorithm on a spin-3/2 (2 qubit) system. The
controlled-not operation needed to implement this algorithm has been
implemented here by evolution under the quadrupolar Hamiltonian. This method
has been implemented for the first time in quadrupolar systems. Since the
quadrupolar coupling is several orders of magnitude greater than the coupling
in weakly coupled spin-1/2 nuclei, the gate time decreases, increasing the
clock speed of the quantum computer.Comment: 16 pages, 3 figure
Adiabatic cross-polarization via intermediate dipolar-ordered state
It is experimentally demonstrated that an adiabatic demagnetization -
remagnetization scheme, where the Zeeman order of abundant nuclei is first
adiabatically converted into the dipolar order, and then, into the Zeeman order
of rare nuclei, can significantly increase polarization of rare nuclei compared
to the conventional cross-polarization technique.Comment: 4 pages, 2 figure
Experimental Implementation of Projective Measurement in Bell Basis
A scheme for direct projection of a quantum state on Bell states is
described. The method is based on constructing an average Hamiltonian with Bell
eigenstates and then, projecting the state on these eigenstates. The projection
is performed by adding the results of a direct and time-reversed evolution.
Experimental demonstration is shown for pairs of dipolar-coupled nuclear spins.Comment: 10 pages, 3 figures, submitte