Limits to quantum computation due to decoherence

Tarun Sanghi, Jha, RM

Jeff Heckey, Shruti R. Patil, Ali Javadi-Abhari +6 more

Quantum computing (QC) offers huge promise to accelerate a range of computationally intensive benchmarks. Quantum computing is limited, however, by the challenges of decoherence: i.e., a quantum state can only be maintained for short windows of time before it decoheres. While quantum error correction codes can protect against decoherence, fast execution time is the best defense against decoherence, so efficient architectures and effective scheduling algorithms are necessary. This paper proposes the Multi-SIMD QC architecture and then proposes and evaluates effective schedulers to map benchmark descriptions onto Multi-SIMD architectures. The Multi-SIMD model consists of a small number of SIMD regions, each of which may support operations on up to thousands of qubits per cycle.

Giuliano Benenti, Giulio Casati

The aim of these lectures is to discuss the limits to quantum computation due to chaos and decoherence effects.

Yakir Aharonov, Alonso Botero, Sandu Popescu +2 more

Pablo Paz Juan

Linus Odenhall

Quantum information and quantum computation is an area of quantum mechanics which utilizes quantum properties of particles in schemes for computation. These quantum schemes have been shown to improve computational capabilities for some systems. In quantum computation, the decoherence problem is a limiting factor. Decoherence is the process of loss of quantum information due to interaction from the environment, which puts a limit to how long a quantum computation is valid. There are ways to limit the effect of decoherence. The idea of a noiseless subsystem is to encode the quantum information in a smaller subsystem of the physical system that is not affected by decoherence. Holonomic quantum computation encodes quantum information in holonomies, making it more robust and less affected by decoherence. In this report, these two concepts are combined by encoding one logical qubit in three physical spin-1 particles. The approach to combine these concepts is entirely analytical. A Hamiltonian acting on the physical system is derived. To achieve a result which is possible to implement experimentally, the analytical derivation utilizes permutation operators to derive the Hamiltonian, which is known to be implementable experimentally. A resulting Hamiltonian to implement the scheme is derived, using only permutaion operators. Both a one-qubit gate and a two-qubit gate is derived, which forms a universal set allowing all possible quantum computation. The resulting scheme seems to only use two-body interactions. The project has shown that holonomic quantum computation in a noiseless subsystem using threephysical spin-1 particles is possible. The resulting scheme only using two-body interactions is of a large interest since this simplifies the experimental implementation.