Talk on "Scaling quantum optics experiments & optimal imaging with number-resolving photon detectors"

23.09.2019 11:00

by Raphael Abrahao, University of Queensland

In order to perform more complex quantum optical experiments, one challenge is the preparation of a large number of single photons. To solve this issue, we demonstrate active demultiplexing of single photons from a quantum dot source. The scheme scales quasipolynomially with photon number, providing a viable technological path for routing n photons in the one temporal stream from a single emitter to n different spatial modes. The performance of our 5 cm integrated photonic chip acting as the demultiplexer is tested and it presents a scalable approach for preparing manifold single photons. [1]

Additionally, I will present our general imaging method based on measuring the complex degree of coherence using linear optics and photon number-resolving detectors. In the absence of collective or entanglement-assisted measurements, our method is optimal over a large range of practically relevant values of the complex degree of coherence. We measure the size and position of a small distant source of pseudo-thermal light, and show that our method outperforms the traditional imaging method. We show that the lack of photon number resolution has only a modest detrimental effect on measurement precision. We simulate imaging using the new and traditional methods showing that the new method improves both image clarity and contrast. [2]

Lastly, I will address the challenges to test computational complexity using a protocol based on linear optical network, Boson Sampling. Proof-of-principle Boson Sampling has been demonstrated, but the number of photons used for these demonstrations is well below any claim of quantum computational advantage. To circumvent this problem, we present a new pathway to scale Boson Sampling experiments by combining continuous-variables quantum information and temporal encoding. By simply switching detection methods the performance of the device can be verified with a number of measurement samples growing polynomially in the number of photons. All building blocks of our proposal have been successfully demonstrated and have shown good performance for scaling. This proposal is within the reach of current technology. [3]

 

References:
[1] Laser & Photonics Reviews 11, 1600297 (2017).
[2] Optimal imaging of remote bodies using quantum detectors. arXiv:1811.02192. (Accepted to PRL.)
[3] Continuous-Variables Boson Sampling: Scaling and Verification. arXiv:1812.08978.

Host: Philip Walther

Location:
Erwin-Schrödinger-HS, 4th floor, Boltzmanngasse 5