Pfaffian-like ground state for 3-body-hard-core bosons in 1D lattices

We propose a Pfaffian-like Ansatz for the ground state of bosons subject to 3-body infinite repulsive interactions in a 1D lattice. Our Ansatz consists of the symmetrization over all possible ways of distributing the particles in two identical Tonks-Girardeau gases. We support the quality of our Ansatz with numerical calculations and propose an experimental scheme based on mixtures of bosonic atoms and molecules in 1D optical lattices in which this Pfaffian-like state could be realized. Our findings may open the way for the creation of non-abelian anyons in 1D systems

Mid-infrared frequency comb spanning an octave based on an Er fiber laser and difference-frequency generation

We describe a coherent mid-infrared continuum source with 700 cm-1 usable bandwidth, readily tuned within 600 - 2500 cm-1 (4 - 17 \mum) and thus covering much of the infrared "fingerprint" molecular vibration region. It is based on nonlinear frequency conversion in GaSe using a compact commercial 100-fs-pulsed Er fiber laser system providing two amplified near-infrared beams, one of them broadened by a nonlinear optical fiber. The resulting collimated mid-infrared continuum beam of 1 mW quasi-cw power represents a coherent infrared frequency comb with zero carrier-envelope phase, containing about 500,000 modes that are exact multiples of the pulse repetition rate of 40 MHz. The beam's diffraction-limited performance enables long-distance spectroscopic probing as well as maximal focusability for classical and ultraresolving near-field microscopies. Applications are foreseen also in studies of transient chemical phenomena even at ultrafast pump-probe scale, and in high-resolution gas spectroscopy for e.g. breath analysis.Comment: 8 pages, 2 figures revised version, added reference

Постулати теорії інтерактивного управління оновленням виробництва

Основні ідеї теорії інтерактивного управління: причини виникнення проблем у сферіекономіки необхідно шукати не тільки саме в цій сфері, але й в таких зальнолюдських сферах як духовна, гуманітарна, соціальна, політична; економіка та її складова–промислове виробництво – розвивається під впливом взаємодії сил культури, влади, ринку, безпеки (КВРБ), а не тільки ринку; взаємодією сил КВРБ необхідно правильно управляти для істотного підвищення продуктивності праці на вітчизняних підприємствах та якості життя в Україні.Basic ideas of theory of interactive management: reasons of origin of problems in the field of economics must be searched not only exactly in this sphere but also in such spheres as spiritual, humanitarian, social, political; economy and its constituent is an industrial production – develops under act of co-operation of forces of culture, power, market, safety (KVRB), but not only market; it is necessary correctly to manage co-operation of forces of KVRB for the substantial increase of the labour productivity on domestic enterprises and quality of life in Ukraine

Dynamical creation of bosonic Cooper-like pairs

We propose a scheme to create a metastable state of paired bosonic atoms in an optical lattice. The most salient features of this state are that the wavefunction of each pair is a Bell state and that the pair size spans half the lattice, similar to fermionic Cooper pairs. This mesoscopic state can be created with a dynamical process that involves crossing a quantum phase transition and which is supported by the symmetries of the physical system. We characterize the final state by means of a measurable two-particle correlator that detects both the presence of the pairs and their size

Adaptive dual-comb spectroscopy in the green region

Dual-comb spectroscopy is extended to the visible spectral range with a set-up based on two frequency-doubled femtosecond ytterbium-doped fiber lasers. The dense rovibronic spectrum of iodine around 19240 cm-1 is recorded within 12 ms at Doppler-limited resolution with a simple scheme that only uses free-running femtosecond lasers

Spin waves in a one-dimensional spinor Bose gas

We study a one-dimensional (iso)spin 1/2 Bose gas with repulsive delta-function interaction by the Bethe Ansatz method and discuss the excitations above the polarized ground state. In addition to phonons the system features spin waves with a quadratic dispersion. We compute analytically and numerically the effective mass of the spin wave and show that the spin transport is greatly suppressed in the strong coupling regime, where the isospin-density (or ``spin-charge'') separation is maximal. Using a hydrodynamic approach, we study spin excitations in a harmonically trapped system and discuss prospects for future studies of two-component ultracold atomic gases.Comment: 4 pages, 1 figur

Dynamical creation of a supersolid in asymmetric mixtures of bosons

We propose a scheme to dynamically create a supersolid state in an optical lattice, using an attractive mixture of mass-imbalanced bosons. Starting from a "molecular" quantum crystal, supersolidity is induced dynamically as an out-of-equilibrium state. When neighboring molecular wavefunctions overlap, both bosonic species simultaneously exhibit quasi-condensation and long-range solid order, which is stabilized by their mass imbalance. Supersolidity appears in a perfect one-dimensional crystal, without the requirement of doping. Our model can be realized in present experiments with bosonic mixtures that feature simple on-site interactions, clearing the path to the observation of supersolidity.Comment: Accepted at Phys. Rev. Let

Strongly correlated quantum physics with cold atoms

This thesis is devoted to exploit strong correlations among ultracold atoms in order to create novel, exotic quantum states. In the first two chapters, we devise dynamical out-of-equilibrium preparation schemes which lead to intriguing final states. First of all, we propose to create the elusive supersolid state via a quantum quench protocol. Supersolids – quantum hybrids exhibiting both superflow and solidity – have been envisioned long ago, but have not been demonstrated in experiment so far. Our proposal to create a supersolid state is perfectly accessible with current technology and may clear the way to the experimental observation of supersolidity. Another out-of-equilibrium preparation scheme is discussed in the second chapter, giving rise to novel Cooper pairs of bosons. Ordinarily, Cooper pairs are composed of fermions – not so in our setup! We show that a Mott state of local bosonic Bell pairs can evolve into a Cooper-paired state of bosons, where the size of the pairs becomes macroscopic. This state can be prepared via a quick, diabatic ramp from the Mott into the superfluid regime. Furthermore, we propose to use bosons featuring conditional-hopping amplitudes in order to create Abelian anyons in one-dimensional optical lattices. We derive an exact mapping between anyons and bosons via a “fractional” Jordan-Wigner transformation. We suggest to employ a laser-assisted tunneling scheme to establish the many-particle state of “conditional-hopping bosons”, thus realizing a gas of Abelian anyons. The fractional statistics phase can be directly tuned by the lasers. The realization of non-Abelian anyons would be especially delightful, due to their significance in topological quantum computation schemes. We propose to employ strongly correlated bosons in one-dimensional optical lattices to create the Pfaffian state – which is known to host non-Abelian anyons as elementary excitations. In this setup, three-body correlations are required to dominate the system, which we model by on-site interactions of atoms with diatomic molecules. Finally, we use strong correlations in one-dimensional systems to create the effect of spin-charge separation, as formulated theoretically first in 1968. For a model of two-component bosons we compute the effective mass of a spin-flip excitation via Bethe Ansatz. In the strongly correlated regime, we show that the effective mass reaches the total mass of all particles in the system. The spin wave thus travels much more slowly than the density wave, giving rise to a strong spin-charge separation.Diese Arbeit widmet sich der Erzeugung neuartiger, exotischer Quantenzustände durch stark korrelierte ultrakalte Atome. Als Erstes zeigen wir, wie der sogenannte suprasolide Zustand in einem optischen Gitter erzeugt werden kann, indem äußere System-Parameter plötzlich verändert werden. Suprasolidität bezeichnet einen neuartigen Materie-Zustand, in dem sich die Atome gleichzeitig sowohl in der festen als auch in der suprafluiden Phase befinden. Eine solche suprasolide Phase wurde bislang experimentell nicht nachgewiesen. Unser Vorschlag, einen suprasoliden Zustand dynamisch zu erzeugen, ist mit gegenwärtiger experimenteller Technik kompatibel und könnte den Weg zum ersten Nachweis der Suprasolidität bereiten. Im zweiten Kapitel beschreiben wir eine weitere dynamische Methode, um neuartige Cooper-Paare aus Bosonen in optischen Gittern zu generieren. Das Konzept der Cooper-Paare, die normalerweise aus antikorrelierten Fermionen bestehen, wird somit auf Bosonen übertragen. Ausgehend von einem Mott-Zustand aus lokalen Bell-Paaren zeigen wir, wie daraus bosonische Cooper-Paare entstehen können. Dazu ist lediglich ein schneller, diabatischer Übergang vom Mott-Regime in das suprafluide Regime nötig. Desweiteren befassen wir uns mit der Herstellung Abelscher Anyonen in optischen Gittern. Wir beweisen, dass Anyonen in einer räumlichen Dimension exakt auf Bosonen abgebildet werden können, wenn deren Tunnelrate von der Besetzung durch andere Bosonen abhängt. Wir beschreiben eine Methode, mit mehreren Raman-Übergängen ein solches System aus „conditional-hopping” Bosonen zu implementieren, was letztlich der Realisierung von Anyonen gleichkäme. Die Austausch-Phase, die die fraktionale Statistik der Anyonen bestimmt, kann durch die Raman-Laser einfach eingestellt werden. In einem weiteren Kapitel befassen wir uns mit nicht-Abelschen Anyonen, deren experimenteller Nachweis besonders reizvoll wäre. Wir zeigen, wie stark korrelierte Bosonen in eindimensionalen optischen Gittern präpariert werden müssen, um den sogenannten Pfaffschen Grundzustand anzunehmen. Elementare Anregungen dieses Zustands können mit nicht-Abelschen Anyonen identifiziert werden. Um den Pfaffschen Zustand zu erzeugen, müssen Dreikörper-Wechselwirkungen – die sonst nur selten in der Natur vorkommen – alle anderen Parameter des Systems dominieren. Wir zeigen wie solche Dreikörper-Korrelationen effektiv durch die Wechselwirkung zwischen Atomen und zwei-atomigen Molekülen realisiert werden können. Schließlich legen wir dar, wie das Phänomen der Spin-Ladungstrennung mithilfe von stark wechselwirkenden Bosonen in einer räumlichen Dimension beobachtet werden könnte. Für eine Mixtur aus Bosonen mit zwei Isospin-Freiheitsgraden bestimmen wir die effektive Masse einer elementaren Spin-Anregung, die durch den Bethe Ansatz exakt berechnet werden kann. Für das stark korrelierte Regime beweisen wir, dass die effektive Masse einer einzelnen Spin-Anregung die Gesamtmasse aller Teilchen annimmt. Die Spin-Welle propagiert damit wesentlich langsamer als die Dichte-Welle der Bosonen, was der maximalen Form der Spin-Ladungstrennung entspricht