Program Archive of the Ortvay Seminar Series 2016 Fall

2016. szeptember 22., csütörtök, 15:00-kor
22nd September 2016., Thursday, 3pm

Sexty Dénes (University of Wuppertal)

"The phase diagram of QCD and the sign problem"

Abstract:

Lattice QCD provides a very successful non-perturbative tool to explore QCD. However, at non-zero baryon-densities it suffers from the sign problem, which invalidates importance sampling simulations. In this talk I will review ideas circumventing the sign problem, focusing on recent developments of methods using analyticity: the complex Langevin equation and the Lefschetz thimble.

2016. október 20., csütörtök, 15:00-kor
20th October 2016., Thursday, 3pm

Tim Pennucci (ELTE, Atomfizikai Tanszék)

"The Present and Future of Pulsar Timing Array Experiments"

Abstract:

In the wake of the recent first detections of kilohertz gravitational waves (GWs) by the ground-based experiment LIGO, pulsar timing array (PTA) experiments are eager to open the next window onto the GW universe in the much lower nanohertz regime. In this talk, I will describe the present state of PTA science, focusing on recent results from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). I will also speculate on the long-term prospects of continuing to produce astrophysically interesting science, since PTA experiments require decade-long timescales to operate. In an important contrast to other GW experiments, I will make the argument that the ancillary science from PTA experiments is commensurate to their primary goals, and justifies continued investment in pushing this frontier of GW astrophysics. 


2016. október 13., csütörtök, 15:00-kor «
13th October 2016., Thursday, 3pm

Rakyta Péter (ELTE, Komplex Rendszerek Fizikája Tanszék)

"Magnetic tuning of ballistic Josephson junctions"

Abstract:

Two-dimensional structures containing superconducting phases are frequently used as building blocks in novel nanoscale devices. For example, the long-range correlation related to the presence of the Cooper pairs is a key ingredient for the realization of quantum entanglement necessary in quantum computing implementations. Motivated by recent experimental works, we studied the Josephson effect in ballistic superconductor-monolayer graphene-superconductor (SGS) junctions. In my talk I will show that a magnetic field can be used to tune the the physical properties of the SGS junctions. I will also describe a novel theoretical approach developed by our group and used to model transport processes in these devices.


2016. október 6., csütörtök, 15:00-kor

6th October 2016., Thursday, 3pm

Roger Bailey (CERN)

"The Large Hadron Collider and Beyond"

Abstract:

The LHC is a very large, technically demanding scientific instrument and is a very large undertaking to build and operate. In this talk we will briefly recall why such a research device is needed before des cribing the main features of the LHC machine and presenting the present performance. Plans for performance upgrades foreseen in the next ten years will be shown, and we will then take a look at what might be on the more distant horizon.

 

Brief bio:

Roger Bailey obtained a PhD in Experimental Particle physics from the University of Sheffield, United Kingdom, in 1979. This was followed by a postdoctoral appointment with Rutherford Laboratory, Oxford, United Kingdom until 1983. During both of these activities he worked on HEP experiments at the CERN SPS, being based at CERN from 1977. In 1983 he joined the Operations Group at the CERN SPS, with responsibility for accelerator operation during the fixed target and p-pbar programs at this facility until 1989. He then joined the LEP commissioning effort, and subsequent operation, becoming Operations Group Leader in the late 1990s. After closure of LEP, he became progressively more involved in the LHC, developing the planning and building the team for LHC commissioning with beam. He was actively involved in LHC commissioning and early operation in the years 2008 to 2010. From 2011 he has been the director of the CERN Accelerator School (CAS). 


2016. október 27., csütörtök, 15:00-kor
27th October 2016., Thursday, 3pm

Iglói Ferenc és Asbóth János (MTA Wigner FK Szilárdtestfizikai és Optikai Intézet)

"Hogy kerül a topológia a szilárdtestfizikába? A 2016. évi fizikai Nobel-díj"

Abstract:

2016-ban a fizikai Nobel-díjat DJ Thouless, FDJ Haldane és JM Kosterlitz kapták, "a topologikus fázisátalakulások és a topologikus fázisok elméleti felfedezéséért". Az előadásban áttekintjük a Nobel-díjjal jutalmazott, 1970-es és 1980-as évekből származó eredményeket. Megmutatjuk, hogy miért voltak ezek meglepőek, hogyan építettek ezekre a 2000-es években kivirágzott topologikus szigetelők elméletében, és hogyan vezethet ez az út a kvantumszámítógép megalkotásához.


2016. november 10., csütörtök, 15:00-kor

10th November 2016., Thursday, 3pm

Illy József (Einstein Papers Project, California Institute of Technology)

"Einstein pörgettyűi / Einstein's Gyros"

Abstract:

Einstein's solitary search for electrogravitational coupling.

Einstein magányos próbálkozása az elektromágnesesség és a gravitáció kapcsolatának kimutatására.


2016. november 24., csütörtök, 15:00-kor

24th November 2016., Thursday, 3pm

Osvay Károly (ELI-HU Non-Profit Ltd.)

"An introduction to the ELI-ALPS Research Infrastructure"

Abstract:

The Attosecond Light Pulse Source (ALPS) facility of the pan-European Extreme Light Infrastructure (ELI) project is designed to build a laser-based research infrastructure in which light pulses of few optical cycles in the infrared or mid-infrared spectral range are generated and used for basic and applied research. These pulses will be used as driving source for the generation of even shorter extreme ultraviolet pulse with durations that can be as short as a few tens of attosecond.

Four laser sources are being implemented at the ELI-ALPS infrastructure, operating in different regimes of repetition rate, peak power, and spectral range. All four light sources deliver pulses with unique parameters: unparalleled fluxes, extreme broad bandwidths and sub-cycle control of the generated fields. The high repetition rate (HR) system delivers TW peak power, < 5 fs pulses at 100 kHz. The 1 kHz repetition rate single cycle (SYLOS) system provides 20 TW pulses with a pulse duration of <5 fs. The petawatt-class high-field (HF) laser will operate at 10 Hz repetition rate with 17 fs pulse duration. The above laser systems operate in a bandwidth window of 600 nm - 1400 nm. These lasers are complemented by the mid-infrared (MIR) laser system, which provides tunable (2.5 µm - 3.9 µm) sub-4 cycle laser pulses at 100 kHz repetition rate with 15 W average power.

These exceptional laser sources will generate a set of secondary sources with incomparable characteristics, including light sources ranging from the THz to the X-ray spectral ranges and particle sources. The laser and secondary sources foreseen at ELI-ALPS will push the frontier of attosecond science in three main directions as coincidence measurements, investigations of highly nonlinear processes in the XUV and X-ray spectral range, and ultrafast valence-shell and core electron dynamics.

Beyond attoscience, the laser sources of ELI-ALPS would also provide regional and national, basic and applied science projects with experimental opportunities in radiobiology, biophotonics, plasma and particle physics.

Activities in the purpose-designed and built building complex will start with the installation of the MIR and the HR laser systems in Spring 2017. Simultaneously, we will also start the assembly of the high harmonic beamlines, the THz laboratory, and nanoplasmonic experiments. The first XUV bursts of light with attosecond duration are expected to be generated by the end of 2017.


2016. december 1., csütörtök, 15:00-kor

1st December 2016., Thursday, 3pm

Kovács Tamás (ELTE Elméleti Fizikai tanszék)

"Komplex hálózatok az exobolygó-rendszerek dinamikájában"

Abstract:

A felfedezett extraszoláris bolygórendszerek számával párhuzamosan olyan új módszerek jelentek meg, mellyekkel ezen rendszerek rövid-, illetve hosszútávú stabilitását vizsgálják. Habár ezen módszerek igen különbözőek, egy alapvető tulajdonságuk azonban közös: mindegyik az észlelésekre támaszkodik, és ezek alapján analitikus, szemi-analitikus vagy numerikus számolásokkal határozzák meg a rendszer fizikai paramétereit, stabilitását. A dinamika rekonstrukciója rövid, mérési zajjal terhelt adatsorokból nagy kihívást jelentő feladat. Az előadásban a nemlineáris idősoranalízis eszköztárát felhasználva mutatom be, miként lehet - a mozgásegyenletek direkt megoldása nélkül - az adott rendszer stabilitására következtetni. Végezetül kitérek arra, milyen kapcsolat hozható az általam vázolt módszer és a komplex hálózatok leírásában használt mennyiségek között.


2016. december 8., csütörtök, 15:00-kor

8th December 2016., Thursday, 3pm

Roy A. Lacey (Stony Brook University, Department of Nuclear Chemistry)

"Finite-Size-Finite-Time Scaling of Susceptibility Proxies Near the QCD Critical Point"
/2016-os Zimányi Nehézionfizikai Téli Iskolával közös előadás/

Abstract:

A major experimental theme at the Relativistic Heavy Ion Collider (RHIC), is the the measurement of observables that could signal the location and character of the critical endpoint (CEP) – the end point of the first-order coexistence curve in the temperature vs. baryon chemical potential (T, µB) plane of the phase diagram for Quantum Chromodynamics (QCD). I will discuss Finite-Size-Finite-Time Scaling of several RHIC measurements linked to the baryon number susceptibility, and show that they lead to scaling functions which provide a potent tool for locating and characterizing the CEP. A recent estimate of the location of the CEP and the critical exponents used to characterize the order of its transition and its static and dynamic universality classes, will be presented as well.