Quantum 2.0 Conference and Exhibition

Fault-Tolerant Quantum Computing with Single-Species Rare-Earth Ion-Doped Crystals

Eva M. González-Ruiz, Hugo Jacinto, Nicolas Sangouard

Published Jan 1, 2025• 0 citations

Abstract

We propose a fault-tolerant quantum computing protocol on a single-species rare-earth-ion-doped crystal, analyzing universal (single- and two-qubit) gate performance, readout optimization, and quantum error correction thresholds. Our findings highlight Eu3+:Y2SiO5 as the best candidate.

DOI: 10.1364/quantum.2025.qm2a.5

Related papers

High-fidelity readout scheme for rare-earth solid-state quantum computing

Andreas Walther, Lars Rippe, Ying Lin Yan +5 more

We propose and analyze a high-fidelity readout scheme for a single-instance approach to quantum computing in rare-earth-ion-doped crystals. The scheme is based on using different elements as qubit and readout ions, where the readout ions are doped into the material at a much lower concentration than the qubit ions. It is shown that by allowing the qubit ion sitting closest to a readout ion to act as a readout buffer, the readout error can be reduced by more than an order of magnitude. The scheme is shown to be robust against certain experimental variations, such as varying detection efficiencies, and we use the scheme to predict the attainable quantum fidelity of a controlled not (cnot) gate in these solid-state systems. In addition, we discuss the potential scalability of the protocol to larger qubit systems. The results are based on parameters which we believe are experimentally feasible with current technology and which can be simultaneously realized.

arXiv:1503.08447Physical Review AAug 10, 201530 citations

Designing gate operations for single-ion quantum computing in rare-earth-ion-doped crystals

Adam Kinos, Lars Rippe, Stefan Kröll +1 more

Quantum computers based on rare-earth-ion-doped crystals show promising properties in terms of scalability and connectivity if single ions can be used as qubits. Through simulations, we investigate gate operations on such qubits. We discuss how gate and system parameters affect gate errors, the required frequency bandwidth per qubit, and the risk for instantaneous spectral diffusion (ISD). Furthermore, we examine how uncertainties in the system parameters affect the gate errors, and how precisely the system needs to be known. We find gate errors for arbitrary single-qubit gates of $2.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ when ISD is not considered and $3.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ when we take heed to minimize it. Additionally, we construct two-qubit gates with errors ranging from $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\ensuremath{\rightarrow}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ over a broad range of dipole-dipole interaction strengths.

arXiv:2108.04498Physical Review ANov 30, 202128 citations

Spectroscopy in Ce3+:Y2SiO5 A preliminary investigation for a single ion readout scheme for quantum computation with rare-earth ion doped crystals

Julio E Hernández

Lund reports on atomic physicsJan 1, 20061 citation

High-connectivity quantum processor nodes using single-ion qubits in rare-earth-ion-doped crystals

Adam Kinos, Lars Rippe, Diana Serrano +2 more

We present two protocols for constructing quantum processor nodes in randomly doped rare-earth-ion crystals and analyze their properties. By varying the doping concentration and the accessible laser tunability, the processor nodes can contain anywhere from only a few tens to almost 1000 qubits. Furthermore, the average number of qubits each qubit can interact with, denoted by the connectivity, can be partly tailored to lie between just a few and roughly 100. We also study how a limited tunability of the laser affects the results and conclude that a tuning range of 100 GHz limits the results to roughly 100 qubits with around 50 connections per qubit on average. In order to construct an even larger processor, the vision is that several of these quantum processor nodes should be connected to each other in a multinode architecture via, e.g., optical interfaces or flying qubits in the form of light. Our results are encouraging for establishing the rare-earth-ion-based systems as a quantum computing platform with strong potential and can serve to focus the efforts within the field.

arXiv:2111.09016Physical Review AMar 4, 202219 citations

An unconventional approach to quantum computing based on rare-earth-ion doped inorganic crystals, including proof of principle experiments.

Nicklas Ohlsson, Tomas Christiansson, Stefan Kröll +3 more

We present a scheme for quantum computing in rare-earth-ion doped inorganic crystals. We use two of the ground state hyperfine levels as the qubit states, with different qubits absorbing light at different frequencies within an inhomogeneously broadened optical transition. Interaction between different qubits is accomplished using the change in permanent dipole moment that is induced at the optical excitation of the ions. The two most important aspects of the scheme have been accomplished experimentally: The isolation of a single qubit in a pure state and interaction between ions absorbing at different frequencies.

Optical Fiber Communication ConferenceJan 1, 20010 citations

A Fabry–Pérot Cavity for Rare-Earth-Ion-Doped Nanocrystals

Andre Nüsslein

This thesis work contributes to the effort of detecting single rare earth ions doped into crystals, an operation crucial for the development of rare earth quantum computer hardware. Doping crystals with rare earth elements, their trivalent ions substitute some of the crystal’s original bonds. These ions have a partially filled 4f shell, protected by the full 5s and 5p shell from the environment which makes them good candidates for qubits. Because not every ion experiences the same electric field from the imperfect crystal, their total linewidth is inhomogeneously broadened. If the doping is sufficiently low and the crystal sufficiently small, each ion undergoes a different optical shift and can thus be addressed separately. Communication between ions happens due to their permanent dipole moments which change according to their energy level. So far no single ions could be detected in Lund because highly doped bulk crystals were used. It was nevertheless tried to construct quantum logic gates using qubits that consisted of an ensemble of ions. Constructing logic gates with these means that every single ion of one qubit needs to be able to communicate with every single ion of another qubit, a method that becomes increasingly difficult when more and more qubits are to be entangled. Connecting as many qubits as possible is a crucial step in building a quantum computer that could outperform classical computers and this could be facilitated if every qubit consisted of only one ion which is the reason for the recent explorations towards nano crystals. This development also makes it possible to address another problem of rare earth ions, their low probability of spontaneous emission. Placing nano crystals into an optical cavity promises the enhancement of spontaneous emission by the Purcell effect. Ideal cavities are Fiber Fabry-Pérot resonators of which one side consists of a mirror coated fiber tip and the other of a plane mirror functioning as the substrate for the nano crystals. It was the aim of this thesis to build a cryostat holder that would bring these two mirrors together with high stability and would allow for vertical and horizontal scanning.

Jan 1, 20190 citations