Qubits break the sound barrier

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Volker Knecht

This chapter gives a summary, conclusion, and outlook on the interplay between AI and physics overall. As an impact of physics on AI, the most recent quantum computer is described. It is the first to exhibit more than 100 qubits and is thus so superior that it can no longer be simulated by a conventional supercomputer. A quantum computer breaking through the “sound barrier” of 1,000 qubits is announced for 2023; experts claim this is the barrier a quantum processor must overcome to be of first efficient use. These advancements will allow the current shortcomings of AI to be overcome and make it more similar to human intelligence which is still superior to AI in various ways. Most of all, human brains are a million times more energy efficient than AI and thus really high-tech! However, the power of AI is increasing exponentially, and technological singularity may be achieved within a few decades. AI researchers expect that artificial general intelligence would be developed by 2040–50. Following thoughts by Stephen Hawking, we could come to the point at which AI would drive science forward by itself, for the sake of technology and human knowledge; the power of AI for physics would then fully unfold.

Andrea Spuntarelli, P. Pieri, Giancarlo Calvanese Strinati

We study the stationary Josephson effect for neutral fermions across the BCS-BEC (Bose-Einstein condensate) crossover, by solving numerically the Bogoliubov-de Gennes equations at zero temperature. The Josephson current is found to be considerably enhanced for all barriers at about unitarity. For vanishing barrier, the Josephson critical current approaches the Landau limiting value which, depending on the coupling, is determined by either pair-breaking or sound-mode excitations. In the coupling range from the BCS limit to unitarity, a procedure is proposed to extract the pairing gap from the Landau limiting current.

Laura Fattaruso

Nir Bitansky, Omer Paneth

The introduction of a non-black-box simulation technique by Barak (FOCS 2001) has been a major landmark in cryptography, breaking the previous barriers of black-box impossibility. Barak's techniques were subsequently extended and have given rise to various powerful applications. We present the first non-black-box simulation technique that does not rely on Barak's technique (or on nonstandard assumptions). Our technique is based on essentially different tools: it does not invoke universal arguments, nor does it rely on collision-resistant hashing. Instead, the main ingredient we use is the impossibility of general program obfuscation (Barak et al., CRYPTO 2001). Using our technique, we construct a new resettably-sound zero-knowledge (rsZK) protocol. rsZK protocols remain sound even against cheating provers that can repeatedly reset the verifier to its initial state and random tape. Indeed, for such protocols black-box simulation is impossible. Our rsZK protocol is the first to be based solely on semi-honest oblivious transfer and does not rely on collision-resistant hashing; in addition, our protocol does not use PCP machinery. In the converse direction, we show a generic transformation from any rsZK protocol to a family of functions that cannot be obfuscated.

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