Emergence of non-abelian magnetic monopoles in a quantum impurity problem

Enderalp Yakaboylu

Institute of Science and Technology Austria


Özet: Recently it was shown that molecules rotating in superfluid helium can be described in terms of the angulon quasiparticles (Phys. Rev. Lett. 118, 095301 (2017)). Here we demonstrate that in the experimentally realized regime the angulon can be seen as a point charge on a 2-sphere interacting with a gauge field of a non-abelian magnetic monopole. Unlike in several other settings, the gauge fields of the angulon problem emerge in the real coordinate space, as opposed to the momentum space or some effective parameter space. Furthermore, we find a topological transition associated with making the monopole abelian, which takes place in the vicinity of the previously reported angulon instabilities. These results pave the way for studying topological phenomena in experiments on molecules trapped in superfluid helium nanodroplets, as well as on other realizations of orbital impurity problems.

Yer : MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih : 9 Ağustos 2017 Çarşamba, 15:00

Magnetarların Yüksek Enerji ve Zamanlama Özellikleri

Sinem Şaşmaz

İstanbul Teknik Üniversitesi


Özet: Yıldız evriminin son aşamalarından biri olan nötron yıldızları şiddetli manyetik alanları, yüksek yoğunlukları ve dönme hızları ile astrofiziğin en ilginç çalışma alanlarından biri olmuştur. Bu nesnelerin uzun süreli ve çeşitli dalgaboylarındaki gözlemleri sayesinde farklı sınıfları keşfedilmiştir. Magnetarlar da sergiledikleri karakteristik özellikleri ile nötron yıldızlarının fiziksel ve evrimsel davranışları ile ilgili yeni problemler sunmalarından dolayı ilgi odağı olmuşlardır. Bu konuşmada öncelikle magnetarların genel özelliklerinden bahsedilip, yüksek enerji gözlemleri sonucunda elde edilen ışınım ve zamanlama özellikleri tartışılacaktır.

Yer : MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih : 6 Nisan 2017 Perşembe, 15:00

Rölativistik Olmayan Uzay-Zamanlar ve Uygulamaları

Deniz Olgu Devecioğlu

İstanbul Teknik Üniversitesi


Özet: Bu konuşmada öncelikle Lifshitz ve Schrödinger uzay-zamanlarının özelliklerini ve rölativistik olmayan alan kuramları ile ilişkilerini özetleyeceğim. Konuşmanın ikinci kısmında rölativistik olmayan alan kuramlarının inşaası, holografik dualite ve Newton-Cartan arkaplanları ile bağlantıları tartışılacaktır.

Kısa Özgeçmiş: Deniz Olgu Devecioğlu lisans eğitimini ODTÜ Fizik bölümünde tamamladı. Doktora derecesini 2016 yılında ODTÜ Fizik bölümünden almıştır. Doktora sonrası çalışmalarını İstanbul Teknik Üniversitesi’nde sürdürmektedir.

Yer : MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih : 16 Mart 2017 Perşembe, 15:00

Preserving the Quantumness of Open Quantum Systems

Göktuğ Karpat

Sao Paulo State University (UNESP)

Özet: Quantum theory is undoubtedly a cornerstone of modern physics and one of the pillars of all natural sciences. Even though it is a century old, some of its counter intuitive features have been started to be exploited on a fundamental level, only for the last two decades, with the emergence of the quantum information science and quantum computation theory. Quantum algorithms and quantum communication protocol can offer tremendous advantage over their corresponding classical counter parts. However, quantum systems are extremely fragile in real world conditions as they tend to rapidly lose their characteristic features and become classical by uncontrollably interacting with their environment . Thus, a major challenge for the practical implementation of quantum protocols and algorithms is the development of reliable methods to retaliate or avoid the destructive effects of this system-environment interaction.

In this talk, we intend to briefly elaborate on our contributions in the literature regarding the development of new techniques to protect precious quantum mechanical features such as coherence, entanglement or more general quantum correlations, which serve as a resource for the quantum communication protocols and quantum algorithms. In particular, to this aim, we shall discuss the significance of decoherence-free subspaces, and non-Markovian memory effects emerging throughout the interaction between the open system and its environment.

Yer : MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih : 9 Mart 2017 Perşembe, 15:00

Weyl-gauged Higher Curvature Gravity Theories and the Spontaneous Generation of Masses of Particles

Suat Dengiz


Özet: In this talk, I will present the Weyl-invariant extension of generic n-dimensional higher curvature gravity theories and the corresponding symmetry-breaking mechanisms for (Anti-) de Sitter and Flat vacua. Here, we will see that the mere existence of (Anti-) de Sitter vacua spontaneously breaks the Weyl’s conformal symmetry in an analogous manner to the Standard model Higgs mechanism. As for flat vacua, the dimensionful parameter comes from the dimensional transmutation in Quantum Field Theories, and thus the gauge symmetry is radiatively broken at loop-level via the Coleman-Weinberg mechanism. From the tree-level unitarity of theories, we will show that the Weyl-gauged Einstein-Gauss-Bonnet theory is the only unitary Weyl-invariant quadratic curvature theory in n-dimension.

Yer : MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih : 29 Aralık 2016 Perşembe, 15:00

Quantification and characterization of quantum non-Markovianity

Barış Çakmak

Koç University

Abstract: All realistic quantum mechanical systems are in interaction with their surroundings. This inevitable interaction between a system and its environment typically results in the loss of quantum features, such as coherence. One important aspect in the study of these so-called open quantum systems is the concept of non-Markovianity, which arises due to memory effects of the environment. Non-Markovian features might enable the system to recover part of the lost coherence and information back from the environment. Although these memory effects have been investigated in the past, only recently an increase in the understanding of non-Markovianity from a quantum information perspective has emerged.
In this talk, I will briefly introduce the different approaches taken in order to quantify non-Markovianity in quantum systems and introduce an entanglement-based measure of non-Markovianity by employing the concept of assisted knowledge, where the environment, acquires information about a system, by means of its measurement apparatus. The assisted knowledge, based on the accessible information in terms of von-Neumann entropy, monotonically increases in time for all Markovian quantum processes. I will demonstrate that the signatures of non-Markovianity can be captured by the non-monotonic behaviour of the assisted knowledge. Moreover, a clear conceptual relation between the entanglement and mutual information based measures of non-Markovianity in terms of the quantum loss and accessible information will be revealed.

Yer : MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih : 15 Aralık 2016 Perşembe, 15:00

Finding odd notes in the spacetime song

Fethi Ramazanoğlu

Koç University

Özet: Gravitational wave detection is now a reality and our most important probe to investigate gravity at the highly dynamical strong-field regime. This new observational tool allows us to see the most bizarre effects of general relativity near neutron stars and black holes. I will spend the first part of the talk to explain the basics of gravitational waves in terms of the physical mechanisms that generate them, their theoretical calculation using state-of-the-art computational tools, and finally their detection. General relativity has not been tested in the dynamical strong-field regime where many field theories are known to break down. Thus, it is natural to analyze the gravitational wave data to find any deviations from general relativity. In the second part of the talk, I will give an overview of what can and cannot be achieved by gravitational wave science in terms of alternative theories of gravitation. I will specifically go through a class of alternative theories based on non-minimally coupled fields, of which the best known example is the spontaneous scalarization scenario of scalar-tensor theories.

Yer : MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih : 7 Aralık 2016 Çarşamba, 15:00