Environment-assisted ultra-sensitive measurements

Achieving measurement sensitivities approaching the so-called Heisenberg limit — the finest precision that any measurement can possibly achieve — may be simpler than originally thought, a theoretical study published in Nature Communications this week reports. In contrast to common belief, quantum entangled states, which are very hard to produce and are very sensitive to environmental disturbances — or decoherence — may not be needed to reach this fundamental limit. This could allow for simpler and more sensitive measurements in areas such as gravitational wave detection and quantum metrology.Daniel Braun and John Martin theoretically describe a measurement principle where, rather than being a destructive force, decoherence processes induced by an environment on a system can collectively enhance the measurement sensitivity on the latter. The researchers envision that the measurement principle can be implemented in a variety of systems, such as photonic crystals, quantum dots coupled to micro-resonators, or atoms trapped in optical cavities.