| 1. |
- Bergenfeldt, Christian, et al.
(author)
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Cooling a micromechanical resonator to its ground state by measurement and feedback
- 2009
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In: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 80:4
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Journal article (peer-reviewed)abstract
- We present an analysis of the cooling of a micromechanical resonator by means of measurement and feedback. The measurements are performed via the coupling to a Cooper-pair box, and although the coupling does not lead to net cooling, the extraction of information and hence entropy from the system leads to a pure quantum state. Under suitable circumstances, the states become very close to coherent states, conditioned on the measurement record, and can hence be displaced to the oscillator ground state.
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| 2. |
- Wesenberg, Janus H, et al.
(author)
-
Scalable designs for quantum computing with rare-earth-ion-doped crystals
- 2007
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In: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 75:1
-
Journal article (peer-reviewed)abstract
- Due to inhomogeneous broadening, the absorption lines of rare-earth-ion dopants in crystals are many order of magnitudes wider than the homogeneous linewidths. Several ways have been proposed to use ions with different inhomogeneous shifts as qubit registers, and to perform gate operations between such registers by means of the static dipole coupling between the ions. In this paper we show that in order to implement high-fidelity quantum gate operations by means of the static dipole interaction, we require the participating ions to be strongly coupled, and that the density of such strongly coupled registers in general scales poorly with register size. Although this is critical to previous proposals which rely on a high density of functional registers, we describe architectures and preparation strategies that will allow scalable quantum computers based on rare-earth-ion-doped crystals.
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