Scheme for reducing decoherence in quantum computer memory

Abstract

Taming decoherence is essential in realizing quantum computation and quantum communication. Here we experimentally demonstrate that decoherence due to amplitude damping can be suppressed by exploiting quantum measurement reversal in which a weak measurement and the reversing measurement are introduced before and after the decoherence channel, respectively. We have also investigated the trade-off relation between the degree of decoherence suppression and the channel transmittance. Experimental verification of the commutation relation for Pauli spin operators using single-photon quantum interference," Phys. Lett. A 374, 4393-4396 (2010).

Environment-Induced Decoherence and the Transition from Quantum to Classical

“…Also, the fact that measurements drastically affect the state of quantum systems [12,13] is somehow suggestive of the difficulties of implementing an error-correcting quantum strategy naively translating the classical error-correcting ideas. However, these expectations were proven to be incorrect when in 1995 Peter Shor created the first quantum errorcorrecting code [75]. His work, once again triggered a lot of activity and over the last four years the theory of Quantum Error Correcting Codes was fully developed.…”

“…So, the question is how to invent codes that protect against arbitrary errors affecting any one of the carrier qubits. A code like this was first presented by Peter Shor [75] and can be constructed using our previous three qubit QECC as a building block. In fact, Shor encodes one qubit using nine carriers organized in three blocks of three qubits each.…”

Zeno dynamics and constraints

“…It is therefore of great interest to endeavor to understand whether decoherence can be controlled and eventually halted [30]: in this context, novel techniques hinging upon the quantum Zeno effect are of interest. Besides the use of quantum error correcting codes [31], the engineering of "decoherence-free" subspaces is also recently being considered and widely investigated [32]. Some mechanisms are actually being proposed, based on the so-called "bang-bang" evolutions and their generalization, quantum dynamical decoupling [33].…”

Silicon-based spin and charge quantum computation

“…It implies that a computer made up of entirely quantum mechanical parts, whose evolution is governed by quantum mechanics, would be able to carry out in reasonably short time prime factorization of large numbers that is prohibitively time-consuming in classical computation, thus revolutionizing cryptography and information theory. Since the invention of Shor's factoring algorithm, it has also been shown that error correction can be done to a quantum system (Shor 1995, Steane 1996, so that a practical quantum computer (QC) does not have to be forever perfect to be useful, as long as quantum error corrections can be carried out. These two key mathematical developments have led to the creation of the new interdisciplinary field of quantum computation and quantum information.…”