May 2022

Abstracts of the QSIT Lunch Seminar, Thursday, May 5, 2022

Modifying the integer quantum Hall effect with cavity vacuum fields

Josefine Enkner - Quantum Optoelectronics Group (Faist group), ETH Zurich

When investigating the system of vacuum cavity fields coupled to Landau levels with magneto-transport, we find that odd filling factors in the integer quantum Hall effect will lose their quantization, while fractional states remain intact. We quantitatively describe this loss of quantization as vacuum field induced resistivity. In our interpretation the interaction with vacuum fields adds a long range perturbation to the system, making it possible for electrons to scatter in between edge and bulk states via an intermediate state containing a virtual particle. This process ultimately breaks the topological protection of the edge states.

Anonymous, Robust Post-Quantum Public Key Encryption

Varun Maram - Applied Cryptography Group (Paterson group), Quantum Center, ETH Zurich

A core goal of NIST's post-quantum cryptography (PQC) standardization process is to produce public-key encryption (PKE) schemes which, even if attacked with a large-scale quantum computer, maintain the security guarantees needed by applications. The main security target in the NIST PQC context has been the notion of so-called 'IND-CCA security', but other applications demand that PKE schemes provide 'anonymity' (defined by Bellare et al., ASIACRYPT 2001), and 'robustness' (defined by Abdalla et al., TCC 2010). Examples of such applications include anonymous cryptocurrencies, searchable encryption, and auction protocols. However, almost nothing is known about how to build post-quantum PKE schemes offering these security properties. In particular, the status of the NIST PQC candidates with respect to anonymity and robustness is unknown.

In this talk, I'll first introduce the area of PQC and describe NIST's ongoing standardization efforts in this regard. Then I'll discuss some main results of our work which address the above anonymity/robustness issue with respect to a subset of NIST PQC candidates -- namely, the finalists "Saber", "Kyber", and "Classic McEliece", and the alternate "FrodoKEM".