10th QSC General Assembly in Amsterdam

 

Programme

10.00 Registration and Coffee/Tea 

10.30 Welcome by Jonas Helsen   

10.40 Léo Ducas (CWI, MI, Leiden) - Lattice-based cryptography and average-case hardness 

11.30 Kirsten Kanneworff (LION, Leiden)  - Towards experimental realisation of quantum position verification 

 

12.00 Lunch  

 

13.30 Ronald de Wolf (QuSoft/CWI, Amsterdam) - Some developments in quantum algorithms 

14.20 Fenglei Gu (QuTech, Delft) - 

          Hybrid quantum repeater chain with trapped Rb neutral atom and Tm-doped AFC quantum memory 

 

14.50 Tea Break  

 

15.20 Evert van Nieuwenburg (LIACS, Leiden) - Quantum games: TiqTaqToe 

15.50 TiqTaqToe tournament 

16:20 Closing by Liubov Markovich  

 

16.25 Drinks & snacks   

18:00 End

 

Ronald de Wolf (QuSoft/CWI, Amsterdam) - Some developments in quantum algorithms
Abstract: Viewed from a distance, the area of quantum algorithms may seem to be dominated by Shor's algorithm for factoring and Grover's algorithm for search, both dating from the mid-1990s. In this talk I will survey some of the main developments that happened since, focusing on two areas: quantum algorithms for optimization problems, and attempts to break post-quantum cryptographic systems.

 

Evert van Nieuwenburg (LIACS, Leiden) - Quantum games: TiqTaqToe

Abstract: If an AI player were to learn to play Quantum Chess, how would it internally represent the quantum state of the game? Would there be any advantages to this AI player being a quantum circuit versus a classical (search) algorithm? These questions can be explored in the framework of quantum games, as well as those of gamified quantum control problems. I will quickly address these topics, and then focus on the other aspects of quantum games: 1) building the future quantum workforce and 2) driving quantum hardware forward.

 

Kirsten Kanneworff (LION, Leiden) - Towards experimental realisation of quantum position verification

Authentication is an important, but also problematic part in communications, also in quantum key distribution (QKD). For many applications, certification of the geographical location of a party would be sufficient for authentication of a communication channel. By using fundamental physical laws, namely, the speed-of-light limit of information transfer, in combination with the no-cloning theorem of quantum mechanics, quantum position verification (QPV) protocols are found to be secure under the condition that attackers can only share a limited amount of pre-shared entanglement.

A key operation of such QPV protocols is the so-called SWAP test where the quantum interference of two photons incident on a beam splitter tests for equality of the photons. In this talk, I will discuss some of the challenges for an experimental realization of such a SWAP test by discussing the need of use of temporally de-multiplexing a single photon source and interfere photons produced several life times apart. In the end I show preliminary results of quantum interference measured in a 4 detector setting which is essential for the SWAP test.

 

Léo Ducas (CWI, MI, Leiden) - Lattice-based Cryptography and Average-case Hardness

In the first part of this talk, I will present the general principal of lattice-based cryptography, namely how to encrypt or authenticate messages using regular grid of points in high-dimensional Euclidean vector spaces. Contrary to factoring or discrete logarithm, the computational problems underlying such cryptographic schemes is not known to be broken via quantum computing. But another of its attractive feature is its provable average-case hardness.

I will explain the theoretical interest of this property for cryptographic construction, and show one such proof of worst-case hardness for a specific class of lattice. Informally, this proof involves walking and jumping randomly over a bunch of donuts.

 

Fenglei Gu (QuTech, Delft) - Hybrid Quantum Repeater Chain with Trapped Rb Neutral Atom and Tm-doped
AFC Quantum Memory
To achieve the quantum internet, quantum repeaters are essential devices for long-distance quantum
communication infrastructure. High-rate quantum repeaters, however, remain a formidable technological challenge
requiring both efficient single photon sources and long-lived, multimode quantum memories. To meet these daunting requirements, hybrid approaches that combine the strengths of different physical hardware constitute a promising route. I will discuss our recent proposal for such a hybrid quantum repeater where single cavity-coupled Rubidium (Rb) atoms can function as entangled single photon sources that are directly compatible both with telecom fibers
and Thulium (Tm) doped crystal multi-mode quantum memories. This combines the excellent single photon emission properties of single Rb atoms with the promising multi-mode capabilities of rare-Earth doped crystals enabling a robust and efficient quantum repeater. Importantly, I will discuss a novel scheme for generating
optical-telecom photon entanglement from single cavity-coupled Rb atoms detailing both cavity, trapping, and pulse design for a robust generation despite common imperfections such as imperfect cavity coupling and laser polarization.