Colloquium: Protecting quantum information against environmental noise

DIETER SUTER; GONZALO AGUSTIN ALVAREZ

REVIEWS OF MODERN PHYSICS

AMER PHYSICAL SOC

Lugar: New York; Año: 2016 vol. 88 p. 41001 - 41001

0034-6861

Quantum technologies represent a rapidly evolving field in which the specific properties of quantum mechanical systems are exploited to enhance the performance of various applications like sensing, transmission and processing of information. Such devices can only be useful if the quantum systems also interact with their environment. However, the interactions with the environment can degrade the specific quantum properties of these systems, like coherence and entanglement. It is therefore essential that the interaction between quantum system and environment is controlled in such a way that the unwanted e↵ects of the environment are suppressed while the necessary interactions are retained. In this Colloquium we give an overview, aimed at newcomers to this field, of some of the challenges that need to be overcome to achieve this goal. A number of techniques have been developed for this purpose in di↵erent areas of physics including magnetic resonance, optics and quantum information. They include the application of static or time-dependent fields to the quantum system, which are designed to average the e↵ect of the environmental interactions to zero. Quantum error correction schemes were developed to detect and eliminate certain errors that occur during the storage and processing of quantum information. In many physical systems, it is useful to use specific quantum states that are intrinsically less susceptible to environmental noise for encoding the quantum information. The dominant contribution to the loss of information is pure dephasing, i.e. through the loss of coherence in quantum mechanical superposition states. Accordingly, most schemes for reducing loss of information focus on dephasing processes. This is also the focus of this article.