Entangled Quantum Metrology

Łukasz Czekaj, Anna Przysiężna, Michał Horodecki +1 more

Which general properties of entangled quantum states are relevant for quantum metrology? As well as showing that enhanced accuracy is not fundamentally related to nonlocality and distillability, the authors are able to demonstrate that tools from quantum metrology may serve as a powerful witness of entanglement.

David S. Simon, Gregg S. Jaeger, Alexander V. Sergienko

Sisi Zhou

Kunkun Wang, Xiaoping Wang, Xiang Zhan +4 more

Quantum metrology overcomes standard precision limits and plays a central role in science and technology. Practically, it is vulnerable to imperfections such as decoherence. Here we demonstrate quantum metrology for noisy channels such that entanglement with ancillary qubits enhances the quantum Fisher information for phase estimation but not otherwise. Our photonic experiment covers a range of noise for various types of channels, including for two randomly alternating channels such that assisted entanglement fails for each noisy channel individually. We simulate noisy channels by implementing space-multiplexed dual interferometers with quantum photonic inputs. We demonstrate the advantage of entanglement-assisted protocols in a phase estimation experiment run with either a single-probe or multiprobe approach. These results establish that entanglement with ancillae is a valuable approach for delivering quantum-enhanced metrology. Our approach to entanglement-assisted quantum metrology via a simple linear-optical interferometric network with easy-to-prepare photonic inputs provides a path towards practical quantum metrology.

Madhura Ghosh Dastidar, Aprameyan Desikan, Vidya Praveen Bhallamudi

Quantum metrology aims at achieving enhanced performance in measuring unknown parameters by utilizing quantum resources. Thus, quantum metrology is an important application of quantum technologies. Photonic systems can implement these metrological tasks with simpler experimental techniques. We present a scheme for improved parameter estimation by introducing entangled generalized coherent states (EGCS) for photonic quantum metrology. These states show enhanced sensitivity beyond the classical and Heisenberg limits and prove to be advantageous as compared to the entangled coherent and NOON states. Further, we also propose a scheme for experimentally generating certain entangled generalized coherent states with current technology.

Vladimir S. Malinovsky