# Paul JulienneNIST and the University of Maryland · Joint Quantum Institute (JQI)

Paul Julienne

Ph. D.

## About

465

Publications

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Introduction

I am retired from a career in theoretical atomic, molecular, and optical physics but remain active in research as an Emeritus Fellow of the Joint Quantum Institute of NIST and the University of Maryland College Park. I am a member of the National Academy of Sciences. A current publication list is at
https://pjulienne.org/publications/ and a CV and Information about my interests in physics is available at
https://pjulienne.org/physics/

## Publications

Publications (465)

Gaining control over chemical reactions on the quantum level is a central goal of the modern field of cold and ultracold chemistry. Here, we demonstrate a novel method to coherently steer reaction flux of a three-body recombination process across different product spin channels. For this, we employ a magnetically-tunable Feshbach resonance to admix...

We theoretically investigate the product-state distribution of weakly bound diatomic van der Waals molecules via ultracold three-body recombination of bosonic alkali atoms. We find a two-level hierarchy of spin propensity rules at zero magnetic field. The primary propensity rule states that nearly all molecular products conserve the total hyperfine...

Efimov trimers are exotic three-body quantum states that emerge from the different types of three-body continua in the vicinity of two-atom Feshbach resonances. In particular, as the strength of the interaction is decreased to a critical point, an Efimov state merges into the atom-dimer threshold and eventually dissociates into an unbound atom-dime...

Efimov states are exotic and counterintuitive three-body quantum states that emerge in the vicinity of two-atom Feshbach resonances. These states exhibit remarkable characteristics as their large spatial extent and extremely weak binding energies following an infinite geometric series, and exist even when interactions are not strong enough to bind...

Feshbach resonances of arbitrary width are typically described in terms of two-channel models. Within these models, one usually considers a single dressed resonance, with the option to extend the analysis by including resonant open-channel features that can drastically change the observed threshold effects. For the strong K40 p-wave resonance studi...

A distinguishing feature of ultracold collisions of bosonic lithium atoms is the presence of two near-degenerate two-body continua. The influence of such a near degeneracy on the few-body physics in the vicinity of a narrow Feshbach resonance is investigated within the framework of a minimal model with two atomic continua and one closed molecular c...

Three-body recombination is a chemical reaction where the collision of three atoms leads to the formation of a diatomic molecule. In the ultracold regime it is expected that the production rate of a molecule generally decreases with its binding energy Eb, however, its precise dependence and the physics governing it have been left unclear so far. He...

Feshbach resonances of arbitrary width are typically described in terms of two-channel models. Within these models, one usually considers a single dressed resonance, with the option to extend the analysis by including resonant open-channel features that can drastically change the observed threshold effects. For the strong $^{40}\mathrm{K}$ p-wave r...

A distinguishing feature of ultracold collisions of bosonic lithium atoms is the presence of two near-degenerate two-body continua. The influence of such a near-degeneracy on the few-body physics in the vicinity of a narrow Feshbach resonance is investigated within the framework of a minimal model with two atomic continua and one closed molecular c...

Three-body recombination is a chemical reaction where the collision of three atoms leads to the formation of a diatomic molecule. In the ultracold regime it is expected that the production rate of a molecule generally decreases with its binding energy $E_b$, however, its precise dependence and the physics governing it have been left unclear so far....

We present a study of interspecies Feshbach resonances in ultracold Li7−133Cs Bose-Bose mixtures. We locate ten interspecies resonances in three different spin-state combinations. By comparing to coupled-channel calculations, we assign six of the resonances to s-wave channels and the rest to p-wave channels. We use the s-wave resonances to refine t...

We present a study of interspecies collision properties in an ultracold $^{7}$Li-$^{133}$Cs Bose-Bose mixture. We locate 10 interspecies Feshbach resonances and carry out coupled-channel calculations to give a consistent assignment of the observed resonances. The calculations also provide a full characterization of the scattering and bound-state pr...

In the vicinity of a narrow Feshbach resonance Efimov features are expected to be characterized by the resonance's properties rather than the van der Waals length of the interatomic potential. Although this theoretical prediction is well established by now, it still lacks experimental confirmation. Here, we apply our recently developed three-channe...

We explore the physical origin and the general validity of a propensity rule for the conservation of the hyperfine spin state in three-body recombination. This rule was recently discovered for the special case of ^{87}Rb with its nearly equal singlet and triplet scattering lengths. Here, we test the propensity rule for ^{85}Rb for which the scatter...

In the vicinity of a narrow Feshbach resonances Efimov features are expected to be characterized by the resonance's properties rather than the van der Waals length of the interatomic potential. Although this theoretical prediction is well-established by now, it still lacks experimental confirmation. Here, we apply our recently developed three-chann...

We explore the physical origin and the general validity of a propensity rule for the conservation of the hyperfine spin state in three-body recombination. This rule was recently discovered for the special case of $^{87}$Rb with its nearly equal singlet and triplet scattering lengths. Here, we test the propensity rule for $^{85}$Rb for which the sca...

Interactions between particles are usually a resource for quantum computing, making quantum many-body systems intractable by any known classical algorithm. In contrast, noise is typically considered as being inimical to quantum many-body correlations, ultimately leading the system to a classically tractable state. This work shows that noise represe...

We study the near-threshold molecular and collisional physics of a strong K40 p-wave Feshbach resonance through a combination of measurements, numerical calculations, and modeling. Dimer spectroscopy employs both radio-frequency spin-flip association in the MHz band and resonant association in the kHz band. Systematic uncertainty in the measured bi...

We study the near-threshold molecular and collisional physics of a strong $^{40}$K p-wave Feshbach resonance through a combination of measurements, numerical calculations, and modeling. Dimer spectroscopy employs both radio-frequency spin-flip association in the MHz band and resonant association in the kHz band. Systematic uncertainty in the measur...

We study three-atom inelastic scattering in ultracold K39 near a Feshbach resonance of intermediate coupling strength. The nonuniversal character of such resonance leads to an abnormally large Efimov absolute length scale and a relatively small effective range re, allowing the features of the K39 Efimov spectrum to be better isolated from the short...

We study three-atom inelastic scattering in ultracold \textsuperscript{39}K near a Feshbach resonance of intermediate coupling strength. The non-universal character of such resonance leads to an abnormally large Efimov absolute length scale and a relatively small effective range $r_e$, allowing the features of the \textsuperscript{39}K Efimov spect...

Free-fermionic systems are a valuable, but limited, class of many-body problems efficiently simulable on a classical computer. We examine how classical simulability of noninteracting fermions is modified in the presence of Markovian dissipation described by quadratic Lindblad operators, including, for example, incoherent transitions or pair losses....

As “Stern-Gerlach first” becomes increasingly popular in the undergraduate quantum mechanics curriculum, we show how one can extend the treatment found in conventional textbooks to cover some exciting new quantum phenomena. Namely, we illustrate how one can describe a delayed choice variant of the quantum eraser which is realized within the Stern-G...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

We perform precise studies of two- and three-body interactions near an intermediate-strength Feshbach resonance in K39 at 33.5820(14) G. Precise measurement of dimer binding energies, spanning three orders of magnitude, enables the construction of a complete two-body coupled-channel model for determination of the scattering lengths with an unpreced...

Several extensions to the Standard Model of particle physics, including light dark matter candidates and unification theories predict deviations from Newton’s law of gravitation. For macroscopic distances, the inverse-square law of gravitation is well confirmed by astrophysical observations and laboratory experiments. At micrometer and shorter leng...

We perform precise studies of two- and three-body interactions near an intermediate-strength Feshbach resonance in $^{39}\mathrm{K}$ at $33.5820(14)\, \mathrm{G}$. Precise measurement of dimer binding energies, spanning three orders of magnitude, enables the construction of a complete two-body coupled-channel model for determination of the scatteri...

Alkaline-earth (AE) atoms have metastable clock states with minute-long optical lifetimes, high-spin nuclei, and SU($N$)-symmetric interactions that uniquely position them for advancing atomic clocks, quantum information processing, and quantum simulation. The interplay of precision measurement and quantum many-body physics is beginning to foster a...

Cooling molecules down to their ground state is an ongoing challenge for atomic and molecular physicists. Further steps in this journey have recently been made, with promising implications.

Using new experimental measurements of photoassociation resonances near the $^1\mathrm{S}_0 \rightarrow \phantom{ }^3\mathrm{P}_1$ intercombination transition in $^{84}$Sr and $^{86}$Sr, we present an updated study into the mass-scaling behavior of bosonic strontium dimers. A previous mass-scaling model [Borkowski et al., Phys. Rev. A 90, 032713 (2...

We measure the modification of the transmission spectra of cold $^{87}$Rb atoms in the proximity of an optical nanofiber (ONF). Van der Waals interactions between the atoms an the ONF surface decrease the resonance frequency of atoms closer to the surface. An asymmetric spectra of the atoms holds information of their spatial distribution around the...

As "Stern-Gerlach first" becomes the new paradigm within the undergraduate quantum mechanics curriculum, we show how one can extend the treatment found in conventional textbooks to cover some of the exciting new developments within the quantum field. Namely, we illustrate how one can employ Dirac notation and conventional quantum rules to describe...

As "Stern-Gerlach first" becomes the new paradigm within the undergraduate quantum mechanics curriculum, we show how one can extend the treatment found in conventional textbooks to cover some of the exciting new developments within the quantum field. Namely, we illustrate how one can employ Dirac notation and conventional quantum rules to describe...

We present high-resolution two-color photoassociation spectroscopy of Bose-Einstein condensates of ytterbium atoms. The use of narrow Raman resonances and careful examination of systematic shifts enabled us to measure 13 bound-state energies for three isotopologues of the ground-state ytterbium molecule with standard uncertainties of the order of 5...

Tracking a trio of rubidium atoms
Crossed molecular beams have provided decades' worth of knowledge into how quantum mechanics governs chemical reactivity. Nonetheless, the technique is generally limited to the collision of two partners. Wolf et al. report on a three-body process with full quantum state resolution. By cooling rubidium atoms to ultr...

We demonstrate the emergence of universal Efimov physics for interacting photons in cold gases of Rydberg atoms. We consider the behavior of three photons injected into the gas in their propagating frame, where a paraxial approximation allows us to consider them as massive particles. In contrast to atoms and nuclei, the photons have a large anisotr...

Hybrid systems of laser-cooled trapped ions and ultracold atoms combined in a single experimental setup have recently emerged as a new platform for fundamental research in quantum physics. This paper reviews the theoretical and experimental progress in research on cold hybrid ion-atom systems which aim to combine the best features of the two well-e...

Feshbach resonances, which allow for tuning the interactions of ultracold atoms with an external magnetic field, have been widely used to control the properties of quantum gases. We propose a~scheme for using scattering resonances as a probe for external fields, showing that by carefully tuning the parameters it is possible to reach a $10^{-5}$G (o...

One of the challenges for fermionic cold atom experiments in optical lattices is to cool the systems to low enough temperature that they can form quantum degenerate ordered phases. In particular, there has been significant work in trying to find the antiferromagnetic phase transition of the Hubbard model in three dimensions, without success. Here,...

Ultracold atoms placed in a tight cigar-shaped trap are usually described in terms of the Lieb-Liniger model. We study the extensions of this model which arise when van der Waals interaction between atoms is taken into account. We find that the corrections induced by the finite range of interactions can become especially important in the vicinity o...

State-to-state chemistry investigates chemical reactions on the most fundamental level. A primary goal of state-to-state chemistry is to determine the quantum states of the final products given the quantum state of reactants. Using the high level control for preparing reactants in the ultracold domain, we demonstrate here a method for investigating...

Ultracold atoms placed in a tight cigar-shaped trap are usually described in terms of the Lieb-Liniger model. We study the extensions of this model which arise when van der Waals interaction between atoms is taken into account. We find that the corrections induced by the finite range of interactions can become especially important in the vicinity o...

State of the art photoassociative measurements of bound state energies in the ground state Yb2 molecule are used to establish limits on non-Newtonian gravity at Yukawa ranges of nanometers.

We observe interspecies Feshbach resonances due to s-wave bound states in ultracold $^{39}$K-$^{133}$Cs scattering for three different spin mixtures. The resonances are observed as joint atom loss and heating of the K sample. We perform least-squares fits to obtain improved K-Cs interaction potentials that reproduce the observed resonances, and car...

A proof-of-concept determination of bounds on non-Newtonian gravity using state of the art photoassociation spectroscopy is presented. The use of Bose-Einstein condensates of ytterbium atoms rather than thermal samples and careful investigation of systematic shifts enabled the determination of a total 13 bound state energies in three isotopomers to...

We propose a novel scheme to efficiently tune the scattering length of two colliding ground-state atoms by off-resonantly coupling the scattering-state to an excited Rydberg-molecular state using laser light. For the s-wave scattering of two colliding ${^{87}}\mathrm{Rb}$ atoms, we demonstrate that the effective optical length and pole strength of...

The multichannel Efimov physics is investigated in ultracold heteronuclear admixtures of K and Rb atoms. We observe a shift in the scattering length where the first atom-dimer resonance appears in the $^{41}$K-$^{87}$Rb system relative to the position of the previously observed atom-dimer resonance in the $^{40}$K-$^{87}$Rb system. This shift is we...

We report the homonuclear photoassociation (PA) of ultracold
${}^{52}\mathrm{Cr}$ atoms in an optical dipole trap. This constitutes the
first measurement of PA in an element with total electron spin $\tilde{S}>1$.
Although Cr, with its ${}^{7}\mathrm{S}_{3}$ ground and
${}^{7}\mathrm{P}_{4,3,2}$ excited states, is expected to have a complicated PA...

We report on the observation of weakly-bound dimers of bosonic Dysprosium
with a strong universal s-wave halo character, associated with broad magnetic
Feshbach resonances. These states surprisingly decouple from the chaotic
backgound of narrow resonances, persisting across many such narrow resonances.
In addition they show the highest reported mag...

Ultracold polar molecules provide an excellent platform to study quantum
many-body spin dynamics, which has become accessible in the recently realized
low entropy quantum gas of polar molecules in an optical lattice. To obtain a
detailed understanding for the molecular formation process in the lattice, we
prepare a density distribution where lattic...

We report photoassociation spectroscopy of ultracold 86 Sr atoms near the intercombination line and provide theoretical models to describe the obtained bound-state energies. We show that using only the molecular states correlating with the 1 S 0 + 3 P 1 asymptote is insufficient to provide a mass-scaled theoretical model that would reproduce the bo...

Optical Feshbach resonances (OFRs) have generated significant experimental interest in recent years. These resonances are promising for many-body physics experiments, yet the practical application of OFRs has been limited. The theory of OFRs has been based on an approximate model that fails in important detuning regimes, and the incomplete theoreti...

Complex quantum systems consisting of large numbers of strongly coupled
states exhibit characteristic correlations in the level spacing distribution
which can be described by Random Matrix Theory. Scattering resonances observed
in ultracold atomic and molecular systems exhibit similar features as a
consequence of their energy level structure. We st...

We report on the observation of weakly-bound dimers of bosonic Dysprosium
with a strong universal s-wave halo character. These states are responsible for
broad magnetic Feshbach resonances. We analyze our findings using a
coupled-channel theory taking into account the short range van der Waals
interaction and a correction due to the strong dipole m...

We investigate the behaviour of single-channel theoretical models of cold and
ultracold collisions that take account of inelastic and reactive processes
using a single parameter to represent short-range loss. We present plots of the
resulting energy-dependence of elastic and inelastic cross sections over the
full parameter space of loss parameters...

We consider low energy threshold reactive collisions of particles interacting
via a van der Waals potential at long range in the presence of external
confinement and give analytic formulas for the confinement modified scattering
in such circumstances. The reaction process is described in terms of the short
range reaction probability. Quantum defect...

We study polar molecule scattering in quasi-one-dimensional geometries.
Elastic and reactive collision rates are computed as a function of collision
energy and electric dipole moment for different confinement strengths. The
numerical results are interpreted in terms of first order scattering and of
adiabatic models. Universal dipolar scattering is...

The quantum mechanical few-body problem at ultracold energies poses severe
challenges to theoretical techniques, particularly when long-range interactions
are present that decay only as a power-law potential. In this paper we review
the techniques and progress in studies of universal few-body physics for
ultracold atoms, particularly those related...

We report photoassociation spectroscopy of ultracold $^{86}$Sr atoms near the
intercombination line and provide theoretical models to describe the obtained
bound state energies. We show that using only the molecular states correlating
with the $^1S_0$$+$$^3P_1$ asymptote is insufficient to provide a mass scaled
theoretical model that would reproduc...

We consider a general problem of inelastic collision of particles interacting
with power-law potentials. Using quantum defect theory we derive an analytical
formula for the energy-dependent complex scattering length, valid for arbitrary
collision energy, and use it to analyze the elastic and reactive collision
rates. Our theory is applicable for bo...

We compare and contrast the wide Feshbach resonances and the corresponding weakly bound states in the lowest scattering channels of ultracold $^{6}\mathrm{Li}$ and $^{7}\mathrm{Li}$. We use high-precision measurements of binding energies and scattering properties to determine interaction potentials that incorporate non-Born-Oppenheimer terms to acc...

We compare and contrast the broad resonances and the corresponding weakly
bound states in the lowest scattering channels of ultracold $^6$Li and $^7$Li.
We use high-precision measurements of binding energies and scattering
properties to determine new interaction potentials, incorporating
non-Born-Oppenheimer terms to account for the failure of mass...

Experimental studies with ultracold atoms have enabled major breakthroughs in
understanding three-body physics, historically a fundamental yet challenging
problem. This is because the interactions among ultracold atoms can be
precisely varied using magnetically tunable scattering resonances known as
Feshbach resonances. The collisions of ultracold...

We compare and contrast the wide Fehbach resonances and the corresponding weakly bound states in the lowest scattering channels of ultracold $^6$Li and $^7$Li. We use high-precision measurements of binding energies and scattering properties to determine new interaction potentials, incorporating non-Born-Oppenheimer terms to account for the failure...

A marriage between theory and experiment has shown that ultracold erbium atoms trapped with laser light and subjected to a magnetic field undergo collisions that are characterized by quantum chaos. See Letter p.475

Studies of cold atom collisions and few-body interactions often require the
energy dependence of the scattering phase shift, which is usually expressed in
terms of an effective-range expansion. We use accurate coupled-channel
calculations on $^{6}$Li, $^{39}$K and $^{133}$Cs to explore the behavior of
the effective range in the vicinity of both bro...

We model the binding energies of rovibrational levels of the RbYb molecule
using experimental data from two-color photoassociation spectroscopy in
mixtures of ultracold $^{87}$Rb with various Yb isotopes. The model uses a
theoretical potential based on state-of-the-art \emph{ab initio} potentials,
further improved by least-squares fitting to the ex...