Scalable designs for quantum computing with rare-earth-ion-doped crystals

Abstract

Due to inhomogeneous broadening, the absorption lines of rare-earth-ion dopands 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 rareearth-ion doped crystals.

Measurement of linewidths and permanent electric dipole moment change of the Ce4f-5dtransition in Y2Yan1, Karlsson2, Rippe3 et al. 2013Phys. Rev. BSelf Cite252270View full textAdd to dashboardCite

“…This means that the number of active ions in one ensemble qubit that interact strongly with one ion in each of the rest of the n − 1 qubits scales as p n−1 . In order to improve this poor scalability, Wesenberg et al proposed several schemes [9]. One approach is to discard the ensemble qubits and instead let each qubit be represented by a single ion (single instance quantum computing).…”

“…One approach is to discard the ensemble qubits and instead let each qubit be represented by a single ion (single instance quantum computing). With sufficient dopant concentration (about 0.2% for Pr:Y 2 SiO 5 ) there will always be sequences of connected ions close enough for carrying out gate operations [9] [10].…”

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“…In the present work polarization of this nuclear spin via photons has been demonstrated. However, using standard methods of coherence transfer from electron to nuclear spins this could be useful for quantum memory 25,26 or quantum processing 27,28 .…”