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Topic Name: The gas molecules polarized at very low temperatures, a new step towards quantum computer
Category: Quantum Computing
Research persons: Deborah Jin and Jun Ye
Location: Colorado, United States
Details
Deborah Jin and Jun Ye of the JILA institute (from collaboration between the University of Colorado at Boulder and NIST) have just published their first results on the creation of a polarized molecules of gas to a temperature of 0 K absolute (350 nK above 0 K). At this temperature, the molecules reach a minimum level of vibrational energy and have more status rotations. They are relatively stable (more than atoms) and easy to control. In such a gas molecules are sensitive to their environment. According to Jin, "at very low temperature, polarized molecules can interact even if they are relatively remote, thanks to their electric dipole moment." They also have a life long on this scale, the order of 30 milliseconds.
To create these molecules researchers have combined gas consisting of potassium atoms (fermions negative) and rubidium (bosons positive). By using magnetic fields and laser high precision, the atoms were assembled at these extreme temperatures. The methods used are based on mechanisms of quantum physics yet little known (and still qualitative models) as the condensation of Bose-Einstein (Bose-Einstein Condensation, or BEC). This implies that these temperatures the atoms behave in unison, ie that the wave functions are identical for each atom. This could then allow a better understanding these mechanisms.
One of the major obstacles to the design of the computer is the quantum decoherence. The decoherence time is a quantum system during which time its properties are not corrupted by the external environment. But the realization of molecular gas represents an important step, because a peculiarity of this gas is stability and durability of its molecules. On the other hand, the quantum computer based on quantum physics idea that two states can exist simultaneously and overlap. Researchers thought replace the conventional bit by the qubit. This is defined as a superposition of several states intermediaries between the "0" and "1" can be represented with a phase. The interest of polarized molecules placed in such extreme conditions is that it is possible to control some of quantum mechanics and thus to control information. According to Jin, "By applying an electric field polarized molecules, it is possible to maintain strong dipole-dipole interactions, then it is possible to reset the system by applying an electric field again."
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