Angle-resolved photoemission spectroscopy of a Fermi–Hubbard system

Research output: Contribution to journalLetter

Abstract

Angle-resolved photoemission spectroscopy (ARPES) measures the single-particle excitations of a many-body quantum system with energy and momentum resolution, providing detailed information about strongly interacting materials1. ARPES directly probes fermion pairing, and hence is a natural technique to study the development of superconductivity in systems ranging from high-temperature superconductors to unitary Fermi gases. In these systems, a remnant gap-like feature persists in the normal state2. Developing a quantitative understanding of these so-called pseudogap regimes may elucidate details about the pairing mechanisms that lead to superconductivity, but this is difficult in real materials partly because the microscopic Hamiltonian is not known. Here, we report on the development of ARPES to study strongly interacting fermions in an optical lattice using a quantum gas microscope. We benchmark the technique by measuring the occupied single-particle spectral function of an attractive Fermi–Hubbard system across the BCS–BEC crossover and comparing the results to those of quantum Monte Carlo calculations. We find evidence for a pseudogap that opens well above the expected critical temperature for superfluidity. This technique may also be applied to the doped repulsive Hubbard model, which is expected to exhibit a pseudogap at temperatures close to those achieved in recent experiments3.

Original languageEnglish (US)
Pages (from-to)26-31
Number of pages6
JournalNature Physics
Volume16
Issue number1
DOIs
StatePublished - Jan 1 2020

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photoelectric emission
superconductivity
fermions
spectroscopy
superfluidity
gases
high temperature superconductors
critical temperature
crossovers
microscopes
momentum
probes
excitation
temperature
energy

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

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title = "Angle-resolved photoemission spectroscopy of a Fermi–Hubbard system",
abstract = "Angle-resolved photoemission spectroscopy (ARPES) measures the single-particle excitations of a many-body quantum system with energy and momentum resolution, providing detailed information about strongly interacting materials1. ARPES directly probes fermion pairing, and hence is a natural technique to study the development of superconductivity in systems ranging from high-temperature superconductors to unitary Fermi gases. In these systems, a remnant gap-like feature persists in the normal state2. Developing a quantitative understanding of these so-called pseudogap regimes may elucidate details about the pairing mechanisms that lead to superconductivity, but this is difficult in real materials partly because the microscopic Hamiltonian is not known. Here, we report on the development of ARPES to study strongly interacting fermions in an optical lattice using a quantum gas microscope. We benchmark the technique by measuring the occupied single-particle spectral function of an attractive Fermi–Hubbard system across the BCS–BEC crossover and comparing the results to those of quantum Monte Carlo calculations. We find evidence for a pseudogap that opens well above the expected critical temperature for superfluidity. This technique may also be applied to the doped repulsive Hubbard model, which is expected to exhibit a pseudogap at temperatures close to those achieved in recent experiments3.",
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Angle-resolved photoemission spectroscopy of a Fermi–Hubbard system. / Bakr, Waseem S.

In: Nature Physics, Vol. 16, No. 1, 01.01.2020, p. 26-31.

Research output: Contribution to journalLetter

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