This event was hosted by the Chief Executives’ Club at Queen’s and the Royal Irish Academy, in association with the School of Maths & Physics.

Professor Hendrik Ulbricht gave his lecture, entitled ‘Testing the foundations of quantum mechanics with levitated mechanical systems’ on Wednesday 8 November from 12.30 - 13.30pm online.

Lecture Abstract

We are using ideas which go back to Professor John Bell such as generating and testing quantum states based on the superposition principle. The overarching goal of our approach is to extend experimental tests of quantum foundations to the macroscopic domain and to large-mass systems. I will discuss experiments on levitated mechanics based on optical, Meissner and Paul trapping nano- and micro-particles in vacuum. Experiments hold promise for testing the quantum superposition principle interferometrically and non-interferometrically. I will explain how that works and where we are with experiments, and emphasise the role of noise in this context. Experiments are pushed in a parameter regime where both quantum states, such as superpositions, and gravity effects are possible to be generated and detected. That low energy non-relativistic regime is expected to provide a new test arena for experiments into the overlap of quantum mechanics and gravity.

Running Order

12.30pm - Introduction from Professor Chris Johnson, Pro Vice-Chancellor, Faculty of Engineering and Physical Sciences of Queen's University Belfast

12.35pm - ‘Testing the foundations of quantum mechanics with levitated mechanical systems’ - Keynote address from Professor Hendrik Ulbricht, Professor of Physics, Southampton University

1.15pm - Q&A Session, hosted by Professor Mauro Paternostro, Head of School of Maths and Physics, Queen's University Belfast

1.30pm - Close by Professor Gerry McKenna, Hon Executive Secretary and President Emeritus, Royal Irish Academy

About our Speaker

Professor Hendrik Ulbricht

Hendrik is Professor of Physics. He obtained his undergraduate degree in physics (Dipl.-Phys.) from the Technical University at Berlin (Germany) and the Albert Einstein Institute (Max Planck Institute for Gravitational Physics, Golm) in 2000 with a theoretical work on Black Hole Thermodynamics. He graduated with a PhD (Dr. rer. nat.) from the Free University of Berlin and the Fritz Haber Institute of the Max Planck Society (Germany) in 2003 with a work on experimental surface science in the group of Nobel Laureate Gerhard Ertl (NP in Chemistry 2007). After a postdoc position at Vanderbilt University in Nashville, US on a Max Kade fellowship and as senior postdoc and Assistant Professor at the University of Vienna (Austria), he joined the Department of Physics & Astronomy in 2008 as a Reader and was promoted to a personal chair in 2014. He leads the Quantum Nanophysics and Matterwave Interferometry research group.

Professor Ulbricht’s current research is Interferometric and Non-Interferometric tests of Quantum Mechanics where the goal is the experimental test of quantum superpositions and the interplay between quantum mechanics and relativity in the macroscopic domain where composite particles contain one million atoms or more; Quantum Technology for Fundamental Physics using Meissner levitation to trap ferromagnetic microparticles at low temperatures and in vacuum. The goal is to use the rotational and translational motion of the ferromagnets to measure tiny forces and fields interacting with the particle; Nanoparticle Trapping, Cooling and Interferometry the goal is the experimental test of quantum theory and eventually also gravity in the context of quantum mechanics by studying nanoparticle motions. This effort ultimately aims to generate spatial quantum superposition states of such nanoparticles, which is directly testing quantum mechanics in the macroscopic domain.

About John Bell

John Stewart Bell - The man who proved Einstein wrong

Bell, John Stewart (1928–90), physicist, was born 28 July 1928 in Belfast, second child among one daughter and three sons of John Bell and Annie Bell (née Brownlee) of Tate's Avenue, Belfast. Both families were of Scottish protestant extraction. Although his father had left school at 12, his mother saw education as a route to a fulfilling life and encouraged her children. However, means were limited and only John was able to stay at school over 14 years of age. He was educated at Old Ulsterville elementary school and Fane St. secondary school before attending the Belfast Technical College, where an academic curriculum, combined with practical courses, provided a sound basis for his future interests in practical and fundamental aspects of science. His interest in books and science from an early age earned him the nickname ‘the prof.’ at home. At the age of 16 (1944) he began working as a junior laboratory assistant in the physics department of QUB under its professors Karl Emelaus and Robert Sloane. Recognising his ability, they encouraged him to attend first-year lectures. The following year, with money saved from his job and some extra support, he enrolled for a degree course. A scholarship was later awarded and he graduated with a first-class degree in experimental physics (1948), staying on to achieve a second degree in mathematical physics (1949). He was particularly interested in quantum mechanics, and encouraged by the crystallographer Paul Peter Ewald (qv), who taught him in his last year at QUB, he applied for a position at the Atomic Energy Research Establishment at Harwell, near Oxford (1949). There he worked under Klaus Fuchs (later arrested for espionage, 1950) on reactor physics before moving to Malvern to work on accelerator design. Here he met Mary Ross, a member of the design group, and they began a collaboration that lasted his lifetime, marrying in 1954.

He published around eighty papers in high-energy physics and quantum field theory. In 1964 he published his greatest contribution to quantum theory, ‘On the Einstein Podolsky Rosen paradox’ (Physics, 1, 195–200), what he called his ‘non-locality theory’, which showed the potential for detecting instantaneous communication between sub-atomic particles that are far apart. This deviates from Einstein's relativity theory, where nothing travels faster than the speed of light. Although his paper was at first ignored, it was taken on board by the physics community. Henry Stapp of the Lawrence National Berkeley Laboratory, California, called his result ‘the most profound discovery of science’ (H. Stapp, ‘Are superluminal connections necessary?’, Nuova Cimento (1977), xl B, 191–205). Another of Bell's papers discredited an earlier ‘proof’ by von Neumann of the impossibility of adding hidden variables to the theory of quantum mechanics.

Unassuming and modest about his own work, he is remembered for his intellectual precision, integrity, and generosity, as well as a keen Ulster sense of humour. An incisive critic, he could be irritated by those less rigorous in their views of quantum physics than himself. He was a frequent visitor to Belfast, where his family remained. His younger brother David, after studying at night, qualified as an electrical engineer and became a professor at Lambton College, Canada, where he wrote several textbooks.