Lorentz Institute

Oct. 16, 2024, 7:30 p.m.
Sitterzaal

Origin of light (and other elementary particles) -- a unification of matter and information

Xiao-Gang Wen

Our world have a lot of mysteries: Why all interaction are gauge interactions? Why all matter elementary particles (such as electrons and quarks) are fermions. Why we have many symmetries even though quantum fluctuations of gravity violate all of them? We find that all those mysteries come from (or can be resolved by) quantum entanglement of many qubits, that form our space. Quantum entanglement of many qubits (the origin of mysteries) is a new physical phenomenon that requires new mathematics -- braided fusion higher category -- to describe, which also becomes the mathematical framework for quantum symmetry .

Nov. 6, 2024, 7:30 p.m.
Sitterzaal

The Quantum Universe

Viatcheslav Mukhanov

I will discuss the recent progress in cosmology, namely, the robust theoretical predictions made back to 80th and how they were confirmed in the Cosmic Microwave Background fluctuations measurements during the last 20 years.

Nov. 8, 2024, 11:30 a.m.
Casimir room, Oort building

Superbunched radiation of a tunnel junction due to charge quantization

Fabian Hassler

A chaotic light source is characterized by the fact that many independent emitters radiate photons with a random optical phase. This is similar compared to a tunnel junction where many independent channels are able to emit photons due to a coupling to an electromagnetic environment. However, in a recent experiment it has been observed that a tunnel junction can deviate from the expectation of chaotic light and is able to emit strongly correlated, superbunched photons. Motivated by this, we study the correlation of the radiation and show that the superbunching originates from the emission of multiple photons which is possible due to the quantization of charge.

Dec. 11, 2024, 7:30 p.m.
Sitterzaal

Challenges to the Lambda CDM cosmology

George Efstathiou

Observations of the cosmic microwave background (CMB) anisotropies provide strong evidence in support of the LCDM cosmology. Nevertheless, a number of 'tensions' have emerged. I will review: (a) recent results from the CMB that have strengthened the evidence in favour of lambda CDM; (b) why it is difficult to explain the discrepancy between the lambda CDM value of the Hubble constant, H0, and the value derived from the Cepheid distance scale; (c) why cosmic shear surveys may indicate a small-scale/large-scale mismatch rather than an inconsistency between early and late time physics; (d) why the recent DESI results suggesting evolving dark energy may be driven by systematic errors; (e) why inflation, a cornerstone of the lambda CDM model, has introduced a new hierarchy problem in cosmology.

Jan. 29, 2025, 7:30 p.m. CE Angelos Michaelides (Cambridge University) TBA

April 30, 2025, 7:30 p.m. CE Renato Renner (ETH Zurich) TBA

May 28, 2025, 7:30 p.m. CE Antonio Acin (ICREA-ICFO) TBA

June 4, 2025, 7:30 p.m. CE Albert-Laszlo Barabasi (Northwestern University) TBA

LS = Lorentz Seminar, Casimir room (276), Oort building
CE = Colloquium Ehrenfestii, De Sitter lecture room, Oort building
SBM = Soft & Biological Matter Seminar, Casimir room (276), Oort building
CS = Cosmology Seminar, Casimir room (276), Oort building
ST = String Theory Seminar, Casimir room (276), Oort building