Thursday at the 5th HLF got underway with a lectures from Manuel Blum, ACM Turing Award recipient, and Efim Zelmanov, who received the Fields Medal. After the lectures, there was a short break and then the Scientific Program rolled on with the Hot Topic of the 5th HLF which revolved around the fundamental principles of quantum computing and what the realistic prospects are in the future. Lectures are available to stream on the HLF video archive and on YouTube. The video coverage of the Hot Topic speakers and panel will be available in the near future.

All of your favorite photos from 5th HLF can be downloaded from the HLF flickr gallery.

Manuel Blum

*“Can a Machine be Conscious? Towards a Computational Model of Consciousness.”*

Thanks to major advances in neuroscience, we are on the brink of a scientific un¬derstanding of how the brain achieves consciousness.

This talk will describe neuro¬scientist Bernard Baars’s Global Workspace Model (GWM) of the brain and propose a formal Turing-Machine-like computational model inspired by it for understanding consciousness. One of several consequences of this Model is the possibility of free will in a completely deterministic world. Another deals with the possibility of build¬ing machines that are conscious. This talk is suitable for college students at all levels, engineers, mathematicians, and anyone who has ever wondered about consciousness.

**Efim Zelmanov**

*“Asymptotic Group Theory”*

The talk is a very general survey of Asymptotic Group Theory. We will focus on growth of groups, growth of graphs and links to Combinatorics and Number Theory.

**Hot Topic at the 5th HLF – Quantum Computing**

This session brought together leading researchers in the field, ranging from the¬orists concerned with the basic principles of quantum computing and algorithmic development to experts in the physical implementation of these ideas. In talks and panel debates they explored what the real prospects are for quantum comput¬ers in the coming years, what are the hurdles yet to overcome – and what op-portunities exist for young researchers entering this exciting field. Philip Ball, who moderated the session, is a science writer and author, and a former editor for physical sciences at Nature. His next book, to be published in 2018, is an examination of current views on the interpretation of quantum mechanics.

**The Panelists**

**Scott Aaronson** – University of Texas

*“Complexity-Theoretic Foundations of Quantum Supremacy Experiments”*

In the near future, there will likely be special-purpose quantum computers with 50 or so high-quality qubits. In this talk, I will discuss general theoretical foundations for how to use such devices to demonstrate “quantum supremacy”: that is, a clear quantum speedup for some tasks, motivated by the goal of overturning the Ex¬tended Church-Turing Thesis (which says that all physical systems can be efficiently simulated by classical computers) as confidently as possible.

**Jay Gambetta** – IBM’s Thomas J. Watson Research Center, Yorktown Heights

*“Approximate quantum computing with near-term devices”*

For many years researchers in quantum information science have made a steady progress with proof-of-principle experiments demonstrating basic building blocks of future quantum computers. Theoretical tools have been developed for under¬standing how such devices might work in the future. With the advent of mod¬est-sized quantum computers such as the IBM Q experience, the field is in the midst of a realignment towards a new era of quantum computing technology. We have entered an era with quantum computing becoming a technology. It is my view that the only viable path in the long term is universal fault-tolerant quantum computing. However, to determine if this is possible and to find value in quantum computing before fault-tolerance is available, I foresee an approaching horizon of ‘approximate quantum computing.’ In this talk I will give some examples of what I mean by approximate quantum computing and outline some of the challenges ahead.

**Seth Lloyd** – Massachusetts Institute of Technology

*“Quantum Computers in Society and in the Universe”*

Quantum computers are approaching the point where they will be able to perform computations that classical computers cannot. Quantum information processing also represents a novel paradigm for understanding problems in physics, such as quantum gravity, that have previous resisted solution. This talk discusses the im¬plications of these advances for human society and for our understanding the uni-verse.

**John Martinis** – University of California at Santa Barbara and Google Quantum AI Laboratory

*“Quantum Hardware at Google: Progress Towards Exponentially Growing Computa¬tional Complexity”*

The quantum hardware group at Google is building superconducting qubit devices for quantum annealing, quantum simulation and gate-model quantum comput¬ing. A large effort this year is focused on demonstrating quantum supremacy on a 49-qubit device. Here the output of a quantum computer can only be checked with a large classical supercomputer, which is limited by the memory storage of the 249 state space. I will show experimental data towards this demonstration from a 9-qubit adjustable-coupler “gmon” device, which implements the basic sampling algorithm of supremacy for a computational (Hilbert) space of about 500. Fidelities in the 90% range indicate that huge Hilbert space computations should be possi¬ble with 20-49-qubit devices, which are presently being designed, built and tested. We have also gone beyond checking whether our quantum computer is operating properly: a quantum-materials simulation shows that complex energy spectra can be accurately predicted on our quantum computer.

**Chris Monroe** – University of Maryland and IonQ

*“Reconfigurable and Scalable Quantum Computing with Atoms”*

Individual atoms are standards for quantum information science, acting as qubits that have unsurpassed levels of quantum coherence, can be replicated and scaled with the atomic clock accuracy, and allow near-perfect measurement. Quantum gate operations between atomic ions are mediated with control laser beams, al¬lowing the qubit connectivity graph to be reconfigured and optimally adapted to a given algorithm or mode of computing. Existing work has shown >99.9% fidelity operations, fully-connected control with up to about 10 qubits, and quantum sim¬ulations with limited control on up to 200 qubits – all with the same atomic archi¬tecture. I will speculate on combining all of this into a single universal quantum computing device that can be co-designed with future applications.

Directly following the Hot Topic at the 5th HLF, all of the participants boarded buses to head to the Technic Museum Speyer and were greeted by a Boeing 747 and the SAP Big Band. Following a welcome drink, everyone went inside to enjoy the cuisine and wander through the various exhibits.