Bretislav Friedrich

Bretislav Friedrich
Fritz Haber Institute of the Max Planck Society | FHI · Department of Molecular Physics

Prof. Dr. rer. nat.

About

214
Publications
22,033
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7,697
Citations
Citations since 2016
52 Research Items
1859 Citations
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300

Publications

Publications (214)
Article
In order to commemorate Alfred Landé’s unriddling of the anomalous Zeeman Effect a century ago, we reconstruct his seminal contribution to atomic physics in light of the atomic models available at the time. Landé recognized that the coupling of quantized electronic angular momenta via their vector addition within an atom was the origin of all the a...
Article
We show that ultra-cold polar diatomic or linear molecules, oriented in an external electric field and mutually coupled by dipole-dipole interactions, can be used to realize the exact Heisenberg XYZ, XXZ and XY models without invoking any approximation. The two lowest lying excited pendular states coupled by microwave or radio-frequency fields are...
Preprint
Full-text available
We show that two seemingly unrelated problems - the trapping of an atom in an optical superlattice (OSL) and the libration of a planar rigid rotor in combined electric and optical fields - have isomorphic Hamiltonians. Formed by the interference of optical lattices whose spatial periods differ by a factor of two, OSL gives rise to a periodic potent...
Preprint
Full-text available
In order to commemorate Alfred Land\'e's unriddling of the anomalous Zeeman Effect a century ago, we reconstruct his seminal contribution to atomic physics in light of the atomic models available at the time. Land\'e recognized that the coupling of quantized electronic angular momenta via their vector addition within an atom was the origin of all t...
Article
Full-text available
We investigated helium-mediated translational and rotational thermalization of the aluminum monofluoride (AlF) molecule at cryogenic temperatures via an ab initio potential energy surface (PES) and quantum multichannel scattering theory. Our examination of the elastic and rotationally inelastic channels revealed that helium is an efficient quencher...
Preprint
Full-text available
A detailed treatment of an electro-optical trap for polar molecules, realized by embedding an optical trap within a uniform electrostatic field, is presented and the trap's properties analyzed and discussed. The electro-optical trap offers significant advantages over an optical trap that include an increased trap depth and conversion of alignment o...
Preprint
Full-text available
We show that ultracold polar diatomic or linear molecules, oriented in an external electric field and mutually coupled by dipole-dipole interactions, can be used to realize the exact Heisenberg XYZ, XXZ and XY models without invoking any approximation. The two lowest lying excited pendular states coupled by microwave or radio-frequency fields are u...
Preprint
Full-text available
We investigated helium-mediated translational and rotational thermalization of the aluminum monofluoride (AlF) molecule at cryogenic temperatures via a new $ab \ initio$ potential energy surface (PES) and quantum multichannel scattering theory. Our examination of the elastic and rotationally inelastic channels revealed that helium is an efficient q...
Article
Full-text available
Prompted by the centenary of Alfred Landé's g‐factor, we reconstruct Landé's path to his discovery of half‐integer angular momentum quantum numbers and of vector coupling of atomic angular momenta—both encapsulated in the g‐factor—as well as point to reverberations of Landé's breakthroughs in the work of other pioneers of quantum physics.
Article
Full-text available
As demonstrated in our previous work [J. Chem. Phys. 149, 174109 (2018)], the kinetic energy imparted to a quantum rotor by a non-resonant electromagnetic pulse with a Gaussian temporal profile exhibits quasi-periodic drops as a function of the pulse duration. Herein, we show that this behaviour can be reproduced with a simple waveform, namely a re...
Chapter
Walther Gerlach’s numerous contributions to physics include precision measurements related to the black-body radiation (1912–1916) as well as the first-ever quantitative measurement of the radiation pressure (1923), apart from his key role in the epochal Stern-Gerlach experiment (1921–1922). His wide-ranging research programs at the Universities of...
Chapter
Motivated by his interest in thermodynamics and the emerging quantum mechanics, Otto Stern (1888–1969) launched in 1919 his molecular beam method to examine the fundamental assumptions of theory that transpire in atomic, molecular, optical, and nuclear physics. Stern’s experimental endeavors at Frankfurt (1919–1922), Hamburg (1923–1933), and Pittsb...
Article
Full-text available
We investigate, both analytically and numerically, the quantum dynamics of a planar (2D) rigid rotor subject to suddenly switched-on or switched-off concurrent orienting and aligning interactions. We find that the time-evolution of the post-switch populations as well as of the expectation values of orientation and alignment reflects the spectral pr...
Preprint
As demonstrated in our previous work [J. Chem. Phys. 149, 174109 (2018)], the kinetic energy imparted to a quantum rotor by a non-resonant electromagnetic pulse with a Gaussian temporal profile exhibits quasi-periodic drops as a function of the pulse duration. Herein, we show that this behaviour can be reproduced with a simple waveform, namely a re...
Article
Our 1. Prologue section applauds some previous celebrations of Peter's inspiring ebullient adventures, including a remarkable new book by Giorgio Benedek and Peter on investigations of surfaces by helium beam scattering. The next sections treat 2. Peter's personal genealogy and 3. Peter's scientific genealogy. Section 4 presents Meanderings and ser...
Preprint
Full-text available
We investigate, both analytically and numerically, the quantum dynamics of a planar (2D) rigid rotor subject to suddenly switched-on or switched-off concurrent orienting and aligning interactions. We find that the time-evolution of the post-switch populations as well as of the expectation values of orientation and alignment reflects the spectral pr...
Book
Full-text available
This Open Access book gives a comprehensive account of both the history and current achievements of molecular beam research. In 1919, Otto Stern launched the revolutionary molecular beam technique. This technique made it possible to send atoms and molecules with well-defined momentum through vacuum and to measure with high accuracy the deflections...
Article
Fritz Haber (1868–1934) and Chaim Weizmann (1874–1952) were both prominent German‐speaking Jewish chemists with rather divergent views on Jewish assimilation and Zionism that only converged upon the rise of the Nazis to power in Germany. While Haber converted to Protestantism and followed the calling of a German patriot during World War One and the...
Article
Full-text available
Superfluid helium nanodroplets comprised of thousands to millions of helium atoms can serve as a reactor for the synthesis of heterogeneous molecular clusters at cryogenic conditions. The cluster synthesis occurs via consecutive pick-up of the cluster building blocks by the helium droplet and their subsequent coalescence within the droplet. The eff...
Article
We investigate the line shape at the electronic origin of single porphine molecules doped into superfluid helium droplets as a function of the droplet size. Helium droplets comprised of less than 105 atoms are generated from an expansion of gaseous helium, while droplets with more than 105 atoms originate from liquid helium. In contrast to our rece...
Article
We study, analytically as well as numerically, the dynamics that arises from the interaction of a polar polarizable rigid rotor with single unipolar electromagnetic pulses of varying length, Δτ, with respect to the rotational period of the rotor, τ r . In the sudden, non-adiabatic limit, Δτ ≪ τ r , we derive analytic expressions for the rotor's wav...
Article
The article reviews recent results on the interactions of polar and polarizable molecules with electromagnetic fields, in particular those carried by unipolar electromagnetic pulses. The results are presented in terms of population quilts and quantum carpets. © 2018, Czech Society of Chemical Engineering. All rights reserved.
Preprint
Full-text available
We study, analytically as well as numerically, the dynamics that arises from the interaction of a polar polarizable rigid rotor with single unipolar electromagnetic pulses of varying length, ∆τ , with respect to the rotational period of the rotor, τ r. In the sudden, non-adiabatic limit, ∆τ τ r , we derive analytic expressions for the rotor's wavef...
Preprint
Full-text available
We study, analytically as well as numerically, the dynamics that arises from the interaction of a polar polarizable rigid rotor with single unipolar electromagnetic pulses of varying length, $\Delta \tau$, with respect to the rotational period of the rotor, $\tau_r$. In the sudden, non-adiabatic limit, $\Delta \tau \ll \tau_r$, we derive analytic e...
Article
We make use of the Quantum Hamilton-Jacobi (QHJ) theory to investigate conditional quasi-solvability of the quantum symmetric top subject to combined electric fields (symmetric top pendulum). We derive the conditions of quasi-solvability of the time-independent Schroedinger equation as well as the corresponding finite sets of exact analytic solutio...
Article
Full-text available
We investigate the solvent shift of phthalocyanine (Pc) doped into superfluid helium droplets and probed by optical spectroscopy at the electronic origin. Our present work complements extant studies and provides results that in part contradict previous conclusions. In particular, the solvent shift does not increase monotonously with droplet radius...
Book
This book is open access under a CC BY-NC 2.5 license. On April 22, 1915, the German military released 167 tons of chlorine gas at Ypres, Belgium. Carried by a long-awaited wind, the chlorine cloud passed within a few minutes through the British and French trenches, leaving behind at least 1,000 dead and 4,000 injured. This chemical attack, which a...
Chapter
Full-text available
There is little doubt that Fritz Haber (1868-1934) was the driving force behind the centrally directed development of chemical warfare in Germany, whose use during World War I violated international law and elicited both immediate and enduring moral criticism. The chlorine cloud attack at Ypres on 22 April 1915 amounted to the first use of a weapon...
Chapter
Full-text available
We examine the life of Clara Haber, nee Immerwahr (1870-1915), including her tragic suicide and its possible relation to the involvement of her husband, Fritz Haber, in chemical warfare. Clara earned a doctorate in chemistry from the University of Breslau, in 1900, as the first woman ever, and married the physical chemist Fritz Haber within a year...
Article
The article reviews the rise of physical and theoretical chemistry from its dawn in the 17th century to the triuphms following the quantum revolution all the way up to the late 1930s. In the final part, prospects for solving many-body problems using quantum computers are discussed. © 2017, Czech Society of Chemical Engineering. All rights reserved.
Article
We have subjected the planar pendulum eigenproblem to a symmetry analysis with the goal of explaining the relationship between its conditional quasi-exact solvability (C-QES) and the topology of its eigenenergy surfaces, established in our earlier work [Frontiers in Physical Chemistry and Chemical Physics {2}, 1-16, (2014)]. The present analysis re...
Article
We investigate several aspects of realizing quantum computation using entangled polar molecules in pendular states. Quantum algorithms typically start from a product state |00...0> and we show that up to a negligible error, the ground states of polar molecule arrays can be considered as the unentangled qubit basis state |00...0>. This state can be...
Article
Full-text available
The properties of molecule-optical elements such as lenses or prisms based on the interaction of molecules with optical fields depend in a crucial way on the molecular quantum state and its alignment created by the optical field. However, in previous experimental studies, the effects of state-dependent alignment have never been included in estimate...
Article
Der deutsch-amerikanische Historiker Fritz Stern ist am 18. Mai 2016 in New York gestorben. Stern widmete sein Leben dem Studium der Kulturgeschichte, besonders Deutschlands und Europas in neuerer Zeit. Im Bewusstsein, dass Deutschlands Aufstieg im 19. Jahrhundert auf seiner wissenschaftlich-technischen Kultur beruhte, schuf Stern eine Galerie der...
Article
The German-born American historian Fritz Stern passed away on May 18, 2016 in New York. Stern dedicated his life's work to the study of European, particularly German, cultural history. Well aware that Germany's rise to preeminence during the 19th century was rooted in its scientific-technological culture, Fritz Stern created a portrait gallery of k...
Article
Full-text available
"Physical chemistry is not just a branch on but the blossom of the tree of knowledge," declared Ostwald, a most vocal advocate of his field, conceived as the basis for all of chemistry. This Essay describes the historical development of physical and theoretical chemistry with a focus on Berlin and Leipzig, its foremost centers in Germany.
Article
Full-text available
„Die physikalische Chemie ist nicht nur ein Zweig, sondern sie ist die Blüte des Baumes des Wissens” – damit feierte Ostwald, dass es der physikalischen und der theoretischen Chemie gelungen war, zur gemeinsamen Ausgangsbasis für die Chemie insgesamt zu werden. Wie das an den beiden historisch wichtigsten Standorten in Deutschland – Berlin und Leip...
Article
We examine the life, work, and legacy of Clara Haber, nee Immerwahr, who became the first woman to earn a doctorate from the University of Breslau, in 1900. In 1901 she married the chemist Fritz Haber. With no employment available for female scientists, Clara freelanced as an instructor in the continued education of women, mainly housewives, while...
Article
Full-text available
We examine the rotational states of a pair of polar $^2\Sigma$ molecules subject to a uniform magnetic field. The electric dipole-dipole interaction between the molecules creates entangled pair-eigenstates of two types. In one type, the Zeeman interaction between the inherently paramagnetic molecules and the magnetic field destroys the entanglement...
Article
Full-text available
Arrays of trapped ultracold molecules represent a promising platform for implementing a universal quantum computer. DeMille has detailed a prototype design based on Stark states of polar $^1\Sigma$ molecules as qubits. Herein, we consider an array of polar $^2\Sigma$ molecules which are, in addition, inherently paramagnetic and whose Hund's case (b...
Article
We present a systematic approach to implementation of basic quantum logic gates operating on polar molecules in pendular states as qubits for a quantum computer. A static electric field prevents quenching of the dipole moments by rotation, thereby creating the pendular states; also, the field gradient enables distinguishing among qubit sites. Multi...
Article
Der Physikochemiker Fritz Haber (1868–1934) ging für sein Ammoniak-Syntheseverfahren zur Herstellung von künstlichem Dünger (“Brot aus der Luft”) in die Geschichte ein. Das Haber-Bosch-Verfahren wurde aber ebenso wichtig für die Erzeugung von Schießpulver. Während des ersten Weltkriegs entwickelte Haber Giftgaswaffen für die deutschen Truppen und w...
Article
Full-text available
We show that congruent electric, magnetic and non-resonant optical fields acting concurrently on a polar paramagnetic (and polarisable) molecule offer possibilities to both amplify and control the directionality of the ensuing molecular states that surpass those available in double-field combinations or in single fields alone. At the core of these...
Article
Full-text available
We undertook a mutually complementary analytic and computational study of the full-fledged spherical (3D) quantum rotor subject to combined orienting and aligning interactions characterized, respectively, by dimensionless parameters $\eta$ and $\zeta$. By making use of supersymmetric quantum mechanics (SUSY QM), we found two sets of conditions unde...
Article
Full-text available
We make use of supersymmetric quantum mechanics (SUSY QM) to find three sets of conditions under which the problem of a planar quantum pendulum becomes analytically solvable. The analytic forms of the pendulum's eigenfuntions make it possible to find analytic expressions for observables of interest, such as the expectation values of the angular mom...
Article
Full-text available
We show that combined permanent and induced electric dipole interactions of linear polar and polarizable molecules with collinear electric fields lead to a sui generis topology of the corresponding Stark energy surfaces and of other observables - such as alignment and orientation cosines - in the plane spanned by the permanent and induced dipole in...
Article
The History Press, Stroud, 2012. 240 pp., hardcover, £ 18.99.—ISBN 978‐0752466019
Article
Full-text available
The endeavor of Otto Sackur (1880-1914) was driven, on the one hand, by his interest in Nernst's heat theorem, statistical mechanics, and the problem of chemical equilibrium and, on the other hand, by his goal to shed light on classical mechanics from the quantum vantage point. Inspired by the interplay between classical physics and quantum theory,...
Article
Full-text available
We present a systematic approach to implementation of basic quantum logic gates operating on polar molecules in pendular states as qubits for a quantum computer. A static electric field prevents quenching of the dipole moments by rotation, thereby creating the pendular states; also, the field gradient enables distinguishing among qubit sites. Multi...
Article
The University of Chicago Press, Chicago, 2011. 405 pp., hardcover, $ 45.00.—ISBN 978‐0226610634
Article
Full-text available
We have experimentally and theoretically investigated the mixed-field orientation of rotational-state-selected OCS molecules and achieved strong degrees of alignment and orientation. The applied moderately intense nanosecond laser pulses are long enough to adiabatically align molecules. However, in combination with a weak dc electric field, the sam...
Article
Full-text available
We show that the electric dipole-dipole interaction between a pair of polar molecules undergoes an all-out transformation when superimposed by a far-off resonant optical field. The combined interaction potential becomes tunable by variation of wavelength, polarization and intensity of the optical field and its dependence on the intermolecular separ...
Article
We review the work and life of Otto Stern who developed the molecular beam technique and with its aid laid the foundations of experimental atomic physics. Among the key results of his research are: the experimental determination of the Maxwell-Boltzmann distribution of molecular velocities (1920), experimental demonstration of space quantization of...
Article
Full-text available
Proposals for quantum computing using rotational states of polar molecules as qubits have previously considered only diatomic molecules. For these the Stark effect is second-order, so a sizable external electric field is required to produce the requisite dipole moments in the laboratory frame. Here we consider use of polar symmetric top molecules....