Opportunities and challenges for photon-number resolution with SNSPD

This year at the Single-Photon Workshop (SPW) in Edinburgh UK, IDQ had the honour of having a talk given by Lorenzo Stasi. Lorenzo presented work that he did during his PhD, done in close collaboration with Giovanni Resta (IDQ) and the Towsif Taher (University of Geneva).

Lorenzo started his presentation by providing a clear motivation on why high-performance PNR and ultrafast detectors are necessary: they can enable many applications, for example

• photonic quantum processors,

• high-rate quantum communication,

• building blocks of quantum networks such as quantum teleportation,

• the characterisation of sources of quantum light.

 

Lorenzo then presented IDQ’s Parallel-SNSPD approach (P-SNSPDs) to achieve high-performance PNR and ultrafast detection. The main features of this latest generation are :

• A unique architecture: 28 interleaved pixels with a design that ensures stable performance at high photon-count rates.

• Efficiency and Speed: high single-photon detection efficiency (SDE) of 88% at 1550 nm and detection rates > 200 million counts per second (Mcps) at 50% efficiency.

• Scalability: Only one coaxial line is required for the 28-pixel system, simplifying integration and enabling more detectors.

• High time Resolution: Jitter below 60ps supports applications requiring precise timing.

This is covered in detail in our technology page and in our Photon-Number Resolution paper.

 

A vision for an ideal PNR detector was then presented.

The ideal performance features are:

• A proper scaling of the n-photon efficiency Pn with the number of photons n. Pn is the probability that n photons incident on the detector are all detected. If Pn = n², where n is the efficiency to detect a single-photon, then we say that the scaling is one of an intrinsic PNR.

• The assignment probability should be 100%. This means that the signal coming from the detector should have no ambiguity about how many clicks occurred. This might seem obvious, but some PNR detectors do not provide this entirely.

 

The ideal “practical” features are:

• Ability to provide PNR resolution without any constraints on the light pulse duration

• Ability to work at high detection rates to allow scaling

• Operational simplicity of the readout scheme including the costs to run one PNR detector.

 

Several PNR approaches were then compared using contour plots. These are:

• P-SNSPDs

• MP-SNSPDs

• Rising-edge analysis of a single-pixel SNSPD

• Several SNSPDs with a beam splitter

• Transition edge sensors (TES)

 

The contour plots are shown below. This highlight that P-SNSPDs an overall excellent coverage of the 5 ideal PNR features what we highlighted.

 

 

Lorenzo’s talk highlighted that P-SNSPDs are playing an important role to meet the requirements of today’s photonic quantum technologies. This was recently exemplified by they fact that P-SNSPDs have been chosen by ORCA Computing to be integrated in the PT-2, ORCA’s latest modular quantum computing system.

Lorenzo’s slide deck can be downloaded here.

 

DOWNLOAD PRESENTATION

 

Get in touch with us if you have questions.