Project Abstract

Project Abstract

Single photons provide unique advantages for quantum information applications due to their robustness, individual addressability and bosonic character. Moreover, the high-speed, low-loss propagation of single photons makes them the best quantum information carriers for quantum networks, delegated quantum cloud computing and novel quantum computation schemes such as Boson Sampling and quantum random walks.

The main goal of this Christian Doppler Laboratory (CDL) is the development of quantum photonics technology for quantum computer networks in real-life scenarios. The core demonstration platform will be an online photonic quantum computer. The quantum resources created in this platform will further be implemented to demonstrate quantum-enhanced classical computing, delegated secure quantum cloud computing and quantum repeater nodes.

In cooperation with Tencent we will address various current challenges for large-scale photonic quantum information processing. We will develop bright multi-photon sources at a telecommunication wavelength to optimize the transmission in integrated and fiber networks, and combine them with efficient superconducting nanowire detectors. In order to overcome the random emission of parametric down-conversion sources we will develop integrated circuits with ultra-fast, low-loss switches. Such integrated optical networks will also be used to obtain quantum control of multi-photon states, enabling the generation of the resource states for quantum repeaters and for the implementation of quantum algorithms and quantum simulations.

Single-photon sources based on semiconductor technology will be investigated for the generation of multi-photon entanglement by exploiting solid-state emitters such as quantum dots6. It was recently shown that solid-state emitters can efficiently emit entangled photons7 and even large strings of these7 in a controlled and pulsed manner, which dramatically reduces the resources required for photonic quantum computers and all-optical quantum repeaters, and thus for a quantum internet.

The first iteration of our online quantum computer will be able to process up to six photons (or qubits) in a controllable integrated photonic circuit. In order to generate public awareness and to obtain valuable input from the vast online community, we will leverage Tencent’s expertise in web access and online applications that will allow the implementation of algorithms and the design of architectures for computations. Such tasks could potentially be integrated into online applications. In addition to the development of the online photonic quantum computer, online access to a true quantum random-number generator, which can be used for various additional applications, will be established.

Building on our online photonic quantum computer setup, we will implement the scalable photonic quantum technology developed within this project for the demonstration of new applications that exploit the unique advantages of single photons. Emphasis will be put on secure quantum computing and quantum-enhanced classical computing for which optical quantum technology is ideally suited. In particular, we aim to demonstrate: (i) practical applications of delegated secure quantum cloud computing and quantum computer repeater nodes for secure quantum communication (ii) hybrid quantum-classical systems, where classical computation is supported by state-of-the-art quantum photonics technology, and (iii) the implementation of quantum machine learning computations using complex integrated network structures, as well as other novel architectures for which photons provide unique advantages.

In summary, the ambition of this CDL is to transition photonic quantum computation from small-scale, proof-of-principle demonstrations into a regime where large-scale, universal quantum computation becomes feasible. Supported by Tencent, the major goals of this CDL are:

• Online access to a photonic quantum computer, with a continuous upgrade of the hardware
• Quantum control and processing of quantum states with tens of photons
• Hyper-encoding to create states with up to 100 qubits
• Demonstration of a new level of data security for quantum computers, quantum clouds, and quantum-enhanced classical computers in real-life scenarios
• Demonstration and benchmarking of complex quantum algorithms and quantum machine learning algorithms using a photonic platform

These achievements will enable three technological breakthroughs on the platform, culminating in:

1. An online scalable photonic quantum computer platform exploiting the concept of measurement-based quantum computing and random-walk quantum computations
2. Photonic quantum-classical hybrid systems that exploit the advantages of classical and quantum technology.
3. The demonstration of photon-based quantum repeater principles for large-scale quantum communication networks.