Calibrating Quantum Detectors - Isis Project No 3960

A robust method for calibrating highly sensitive photon number resolving detectors used in emerging optical applications such as quantum imaging, spectroscopy, lithography and quantum computing.

Marketing Opportunity

Much of the revenue generated from various calibration techniques arises from the work of national laboratories throughout the world that are often the practitioners of detector standards. The Oxford invention has a wide range of applications especially where photon-number resolution is necessary for large algorithms such as emerging optical quantum information protocols.

The Oxford Invention

Optical detectors are used in numerous industries, from medical sciences to radiation monitors for ancient artefacts in museums. Conventional classical calibration methods use previously characterized light sources to estimate the overall efficiency of a detector.  However, these approaches cannot be extended to detectors working at quantum level, as they will require light sources with extremely low powers (femtowatt) to avoid saturation and such sources are impractical.  Another approach (Klyshko Scheme) that uses the statistical character of light has been proposed to solve the limitations of classical approaches but has inherent issues too.

Oxford researchers have devised a generalised and robust method for absolute efficiency estimation of photon number resolving detectors (PNRD). The figure below shows that constant efficiencies have been achieved for two PNRDs using the Oxford calibration method. The conventional Klyshko method breaks down at higher photon numbers leading to an over estimation of the detectors efficiency. The Oxford invention has several other advantages:

• Provides measurement redundancy
• Achieves lower absolute error
• Allows in-situ calibration
• Allows use of brighter light sources including amplified pulse pumped sources
• Can also be applied to Binary or pseudo photon-number resolving detectors

Patent Status

This work is the subject of a UK patent application, and Isis would like to talk to companies interested in commercialising this opportunity. Please contact the Isis Project Manager to discuss this further.

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