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Effects of Decoherence and Imperfections for Quantum Information Processing

Objective

The project investigates decoherence and imperfection effects for quantum information processing. It determines the accuracy bounds and the time scales for reliable computations on realistic quantum processors with the help of a numerical code package, which will be created specifically for this purpose. The project also develops new efficient quantum algorithms for important physical problems including electron transport in disordered materials, metal-insulator transitions and complex problems of non-linear classical dynamics. Quantum error-correcting codes will be tested on these new algorithms using the special-purpose code package. This will permit to simulate realistic quantum processors with up to 30 qubits and to determine optimal regimes for their operation under different experimental conditions. The project investigates decoherence and imperfection effects for quantum information processing. It determines the accuracy bounds and the time scales for reliable computations on realistic quantum processors with the help of a numerical code package, which will be created specifically for this purpose. The project also develops new efficient quantum algorithms for important physical problems including electron transport in disordered materials, metal-insulator transitions and complex problems of non-linear classical dynamics. Quantum error-correcting codes will be tested on these new algorithms using the special-purpose code package. This will permit to simulate realistic quantum processors with up to 30 qubits and to determine optimal regimes for their operation under different experimental conditions.

OBJECTIVES
The aim of this project is the investigation of decoherence and error correction in quantum processors solving physical problems for which new and useful results may be achievable using 40-60 qubits. New algorithms will be developed for these problems, which will include complex quantum dynamics, non-linear classical evolution, electron transport in disordered materials and metal-insulator transitions. A numerical code package will be developed to simulate these new algorithms and to model decoherence and imperfection effects for realistic quantum computers with up to 30 qubits. Using this code package, decoherence time scales and critical thresholds for multi-qubit residual imperfections will be determined. Quantum error-correcting codes will be tested with this package to reduce these decoherence effects in the specific algorithms developed within this project.

DESCRIPTION OF WORK
We will investigate the effects of various decoherence sources on existing and newly developed efficient quantum algorithms simulating important physical problems, considering decoherence produced by noisy gates modeled by random unitary rotations as well as more general environment-induced noise processes. In parallel the effects of internal static imperfections, including residual couplings between qubits and static level spacing fluctuations for individual qubits, will be investigated. We will develop a numerical code package capable of modelling these imperfections and decoherence effects for a given experimental realization of a quantum processor and thereby determine the bounds for reliable quantum computation. We will develop new efficient quantum algorithms for computationally hard physical problems such as simulation of many-body quantum systems, Anderson transition, electron transport and chaotic classical dynamics. Our numerical code package will model the realistic effects of decoherence and imperfections in the new quantum algorithms developed. We plan to be able to handle up to 30 qubits for noisy gates and quantum trajectory methods and up to 15 qubits for density matrix methods. Using our code, it will be possible to model the static imperfections typical for a given experimental implementation of a quantum processor. Quantum error correction codes will be numerically tested to stabilize newly developed quantum algorithms against decoherence and static residual couplings between qubits. We will use methods from quantum information theory, the theory of complex classical and quantum dynamical systems, random matrix theory, mesoscopic physics and many-body quantum physics combined with our broad experience in numerical simulations of these systems.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

UNIVERSITE PAUL SABATIER
Address
118, Route De Narbonne
31062 Toulouse
France

Participants (3)

ISTITUTO NAZIONALE PER LA FISICA DELLA MATERIA
Italy
Address
Corso F. Perrone 24
16152 Genova
ROYAL HOLLOWAY AND BEDFORD NEW COLLEGE
United Kingdom
Address
Egham Hill
TW20 0EX Egham, Surrey
TECHNISCHE UNIVERSITAET DARMSTADT
Germany
Address
Karolinenplatz 5
64289 Darmstadt