An official website of the United States government
We present an expression for the spectral gap, opening up new possibilities for performing and accelerating spectral calculations of quantum many-body systems. We develop and demonstrate one such possibility in the context of tensor network simulations. Our approach requires only minor modifications of the widely used simple update method and is computationally lightweight relative to other approaches. We validate it by computing spectral gaps of the 2D and 3D transverse-field Ising models and find strong agreement with previously reported perturbation theory results. Published by the American Physical Society2024
more »
« less
Probing molecular spectral functions and unconventional pairing using Raman spectroscopy
An impurity interacting with an ultracold Fermi gas can form either a polaron state or a dressed molecular state, the molaron, in which the impurity forms a bound state with one gas particle. This molaron state features rich physics, including a negative effective mass around unitarity and a first-order transition to the polaron state. However, these features have remained so far experimentally inaccessible. In this work we show theoretically how the molaron state can be directly prepared experimentally even in its excited states using Raman spectroscopy techniques. Initializing the system in the ultrastrong coupling limit, where the binding energy of the molaron is much larger than the Fermi energy, our protocol maps out the momentum-dependent spectral function of the molecule. Using a diagrammatic approach we furthermore show that the molecular spectral function serves as a direct precursor of the elusive Fulde-Ferell-Larkin-Ovchinnikov phase, which is realized for a finite density of fermionic impurity particles. Our results pave the way to a systematic understanding of how composite particles form in quantum many-body environments and provide a basis to develop new schemes for the observation of exotic phases of quantum many-body systems. Published by the American Physical Society2024
more »
« less
- PAR ID:
- 10641675
- Publisher / Repository:
- American Physical Society
- Date Published:
- Journal Name:
- Physical review research
- Volume:
- 6
- Issue:
- 2
- ISSN:
- 2643-1564
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Toward more efficient schemes for achieving deeply degenerate molecular Fermi gases, we study anisotropic thermalization in dilute gases of microwave shielded polar molecular fermions. For collision energies above the threshold regime, we find that thermalization is suppressed due to a strong preference for forward scattering and a reduction in total cross section with energy, significantly reducing the efficiency of evaporative cooling. We perform close-coupling calculations on the effective potential energy surface derived by Deng [] to obtain accurate two-body elastic differential cross sections across a range of collision energies. We use Gaussian process regression to obtain a global representation of the differential cross section over a wide range of collision angles and energies. The route to equilibrium is then analyzed with cross-dimensional rethermalization experiments, quantified by a measure of collisional efficiency toward achieving thermalization. Published by the American Physical Society2024more » « less
-
We simulate the dynamics of Rydberg atoms resonantly exchanging energy via two-, three-, and four-body dipole-dipole interactions in a one-dimensional array. Using simplified models of a realistic experimental system, we study the initial-state survival probability, mean level spacing, spread of entanglement, and properties of the energy eigenstates. By exploring a range of disorders and interaction strengths, we find regions in parameter space where the three- and four-body dynamics either fail to thermalize or do so slowly. The interplay between the stronger hopping and weaker field-tuned interactions gives rise to quantum many-body scar states, which play a critical role in slowing the dynamics of the three- and four-body interactions. Published by the American Physical Society2024more » « less
-
The structure of hadronic form factors at high energies and their deviations from perturbative quantum chromodynamics provide insight on nonperturbative dynamics. Using an approach that is consistent with dispersion relations, we construct a model that simultaneously accounts for the pion wave function, gluonic exchanges, and quark Reggeization. In particular, we find that quark Reggeization can be investigated at high energies by studying scaling violation of the form factor. Published by the American Physical Society2025more » « less
-
We explore how the spectral phase of attosecond pulse trains influences the optical cross section in transient absorption (TA) spectroscopy. The interaction of extreme ultraviolet (XUV) and time-delayed near-infrared (NIR) fields with an atomic or molecular system governs the dynamics. As already shown in RABBITT experiments (Reconstruction of Attosecond Beating by Interference of Two-Photon Transitions), the spectral phase of the XUV pulses can be extracted from the photoionization spectrum as a function of the time delay. Similarly, this XUV phase imprints itself on delay-dependent optical cross-section oscillations. With a perturbative analytical approach and by simulating the quantum dynamics both in a few-level model and via solving the time-dependent Schrödinger equation for atomic hydrogen, we reveal the similarity between the spectral phase in RABBITT and TA spectroscopy. Published by the American Physical Society2025more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1103/PhysRevResearch.6.023239
