Events

Understanding the properties of real materials requires the incorporation of multiple degrees of freedom into the theoretical modeling. In this research, we focus on the coupling of electrons to phonons. We developed a comprehensive matrix-product-states based schemes that allows to compute spectral functions, optical conductivity and thermal conductivity of one-dimensional Holstein chains, both for the polaron case and half filling, and at finite temperatures. These techniques work well in t...

Description of the relaxation or thermalization of the strongly correlated system close to the integrable point remains a challenge. Although the fate of such systems is ultimately an ergodic dynamic, the road to it could take an extremely long time and can display some exotic (type of integrability breaking-dependent) behavior. On the one hand, many extremely long-time scales - reminiscent of integrals of motions - prevent numerical simulations from reaching an unbiased conclusion on such sy...

The ability to switch magnets between two stable bit states is the main principle of digital data storage technologies since the early days of the computer. Since our demonstration of magnetization reversal by a single 40 femtosecond laser pulse, the manipulation of spins by ultra-short laser pulses has developed into an alternative and energy efficient approach to magnetic recording. Though originally thought to be due to an optically induced effective field, later studies demonstrated that ...

Driving certain cuprates and organic materials has been shown to induce THz optical properties reminiscent of superconductivity far above the equilibrium transition temperature. However, the magnetic response of these non-equilibrium states remains unexplored. This study investigates whether these states exhibit a Meissner effect, expelling external magnetic fields, and examines their response to changing magnetic fields on sub-picosecond time scales.Our methodology involves studying the ultr...

Many modern devices are based on the operations with spins. They require the preparation of the initial state: with spin polarization or at least with spin correlations. There is a limited number of conventional methods to achieve this: application of ferromagnetic materials, current to spin conversion due to spin-orbit interaction and static polarization in high magnetic fields. We show the existence of another way to achieve spin polarization in non-magnetic solid-state devices. It requires...

When a continuous symmetry is spontaneously broken, two types of collective modes emerge: phase and amplitude mode fluctuations of the order parameter. The latter is a massive excitation living at the edge of the gap. Recently, signatures of the amplitude mode were observed in photo-doped superconductors using third-harmonics generation in the terahertz regime, which opened the field of nonlinear light-amplitude mode coupling.We will show that a weak photo-excitation in superconductors leads ...