Theoretical Investigation of Robust Quantum Computing in Rare-earth-ion Doped Crystals PDF Download
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Author: Ingela Roos
Publisher:
ISBN:
Category :
Languages : en
Pages : 64
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Author: Ingela Roos
Publisher:
ISBN:
Category :
Languages : en
Pages : 64
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Author: David Lee McAuslan
Publisher:
ISBN:
Category : Dielectric resonators
Languages : en
Pages : 182
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Author: Nicklas Ohlsson
Publisher:
ISBN:
Category : Ionic crystals
Languages : en
Pages : 144
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Author: Probst, Sebastian
Publisher: KIT Scientific Publishing
ISBN: 373150345X
Category : Physics
Languages : en
Pages : 156
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Book Description
Hybrid quantum circuits interfacing rare earth spin ensembles with microwave resonators are a promising approach for application as coherent quantum memory and frequency converter. In this thesis, hybrid circuits based on Er and Nd ions doped into Y?SiO? and YAlO? crystals are investigated by optical and on-chip microwave spectroscopy. Coherent strong coupling between the microwave resonator and spin ensemble as well as a multimode memory for weak coherent microwave pulses are demonstrated.
Author: Tomas Christiansson
Publisher:
ISBN:
Category :
Languages : en
Pages : 54
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Author: John Glen Bartholomew
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ISBN:
Category : Quantum computers
Languages : en
Pages : 878
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In the last decade, the solid-state rare-earth-ion system has demonstrated increasing appeal for quantum computation. Despite this progress, two hardware limitations prevent a scalable implementation. These current limitations are the inability to miniaturise and the inability to perform single-ion qubit readout. This thesis addresses both these limitations and demonstrates that neither poses a fundamental restriction on increasing the scale of rare-earth-ion quantum computers. The challenge in miniaturising rare-earth-ion quantum hardware arises from the increases in homogeneous and inhomogeneous broadening that accompany micron-scale architectures. The success of miniaturised architectures, such as waveguides, depends on the properties of bulk ions being preserved within microns of the crystal surface. In addition, bulk ion properties must also be preserved in regions of high residual stress resultant from waveguide fabrication. The inhomogeneous and homogeneous properties of near-surface ions and ions in highly stressed environments in Pr3+:Y2SiO5 were studied via white light interferometry combined with micron resolution fluorescence microscopy. It was found that the bulk ion properties could be preserved both near the surface and in highly stressed regions close to micron-scale surface damage. The observation of excess inhomogeneous and homogeneous broadening was found to be consistent with the damage present at the crystal surface. The main outcome of the study was a set of waveguide fabrication guidelines to ensure that the appealing properties of bulk crystals can be maintained in a miniaturised architecture. The current inability to perform single-ion qubit readout is a consequence of the difficulty in isolating a single ion and lack of cyclicity in rare-earth-ion materials. Two techniques are proposed to form a solution: Stark activation and Zeeman enhanced cyclicity. When combined, these techniques offer direct readout for single-ion frequency-based quantum computing. Stark activation is designed to isolate a single rare-earth ion in a macroscopic crystal. The proposal is based on defining the condition for resonant excitation through a spatially varying electric field. A proof-of-principle experiment successfully created a 10 um absorption region within a millimetre thick crystal. In addition, the signal-to-noise ratio of the technique was characterised in experiments probing Pr3+:Y2SiO5 at the single-ion level. Future improvements to the apparatus should allow the nanometre spatial resolution and the noise level to be reduced to allow single-ion optical detection. High cyclicity is essential for high-fidelity optical readout of a single-ion qubit. Zeeman enhanced cyclicity achieves this by manipulating the hyperfine structure of the resonant crystal field levels to induce strong hyperfine selection rules. The technique is shown to be applicable to even the lowest symmetry sites. The simulated level of cyclicity in Pr3+:Y2SiO5 was greater than 99.99% by applying a 10 T field. The investigation of scalability in the rare-earth-ion system marks a movement away from the traditional ensemble-based methods in macroscopic crystals. This study required an understanding of these materials at a single-ion level and the development of high spatial resolution spectroscopic techniques. These advances extend the ability to engineer rare-earth-ion systems for applications including, but not limited to, quantum computing.
Author: Jevon Joseph Longdell
Publisher:
ISBN:
Category : Quantum computers
Languages : en
Pages : 184
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"A great deal of theoretical activity has resulted from blending the fields of computer science and quantum mechanics. Out of this work has come the concept of a quantum computer, which promises to solve problems currently intractable for classical computers. This promise has, in turn, generated a large amount of effort directed toward investigating quantum computing experimentally. Quantum computing is difficult because fragile quantum superposition states of the computer's register must be protected from the environment. This is made more difficult by the need to manipulate and measure these states.
Author: Adam Kinos
Publisher:
ISBN: 9789177535430
Category :
Languages : en
Pages : 203
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Author: Janus Halleløv Wesenberg
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Rose Ahlefeldt
Publisher:
ISBN:
Category : Crystals
Languages : en
Pages : 438
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This thesis presents a spectroscopic study of the 7F0-5D0 transition of Eu3+ in EuCl3.6H2O, which is used to evaluate the potential performance of a quantum computing system implemented in EuCl3.6H2O and, more generally, in stoichiometric rare earth crystals. EuCl3.6H2O has one of the narrowest optical inhomogeneous linewidths of any solid but this linewidth is shown to be still much larger than that required for practical quantum computing in a rare earth crystal. To assess the possibility of reducing the linwidth, the contributions of isotopic impurities to both the optical linewidth and line structure were investigated, and ligand isotopes were identified as a major source of both inhomogeneous broadening and structure on the optical transition, suggesting that the linewidth could be substantially reduced by isotopically purifying EuCl3.6H2O. The effect of ligand isotopes on the optical lifetime and coherence time was also investigated. It was found that fully deuterating the crystal to EuCl3.6D2O substantially improves both the lifetime and coherence time. The satellite lines formed in the optical spectrum of a rare earth crystal when it is doped with another rare earth are proposed as qubits. A crucial step in characterising EuCl3.6H2O for quantum computing is associating these satellite lines in EuCl3.6H2O with crystallographic sites. A new method for associating sites with lines, which works for low symmetry crystals such as EuCl3.6H2O, is presented. This method involves modelling the splitting of the ground state hyperfine levels caused by the magnetic dipole-dipole interaction between a Kramers dopant and the Eu3+ ion. Using this method, most of the outer satellite lines in rare earth doped EuCl3.6H2O were assigned to crystallographic sites. It has been proposed that the electronic interactions between these satellite lines be used to enact two-qubit gates in a rare earth quantum computer. These interactions were measured between a number of different satellite lines using a new two-laser spectral holeburning technique. Interactions of up to 46.081 +- 0.005 MHz were observed, and this was the first time that electronic interactions between weakly coupled rare earth ions had been measured. The two most common interactions identified between rare earth ions in solids are electric dipole-dipole and exchange, but the observed interactions are stronger than expected from a electric dipole-dipole model and occur at too large a distance to be superexchange. It is shown that the development of a moderate-sized quantum processor, one with more than 10 qubits, in a stoichiometric rare earth crystal is feasible provided that the optical inhomogeneous linewidth is reduced below 1 MHz. Demonstrations of three or four qubit devices should be possible using existing materials.
