Entangled phase of simultaneous fermion and exciton condensations realized

Abstract

Fermion-exciton condensates (FECs)-computationally-and theoretically-predicted states that simultaneously exhibit character of superconducting states and exciton condensates-are novel quantum states whose properties may involve a hybridization of superconductivity and the dissipationless flow of energy. Here, we exploit prior investigations of superconducting states and exciton condensates on quantum devices to identify a tuneable quantum state preparation entangling the wavefunctions of the individual condensate states. Utilizing this state preparation, we prepare a variety of fermion-exciton condensate states on quantum computers-realizing strongly-correlated FEC states on current, noisy intermediate-scale quantum devices-and verify the presence of the dual condensate via post-measurement analysis. This confirmation of the previously-predicted condensate state on quantum devices as well as the form of its wavefunction motivates further theoretical and experimental exploration of the properties, applications, and stability of fermion-exciton condensates.

Simultaneous fermion and exciton condensations from a model Hamiltonian

“…II and Appendix A) for systems of even particle numbers ranging from N = 4 to N = 10 particles in r = 2N orbitals. These fermion-exciton condensates are shown to be described by wavefunctions which are entanglements of wavefunctions from BCS-like superconductivity and Lipkin-like exciton condensation-consistent with our prior predictions for the large-N thermodynamic limit [39] as well as those we observed experimentally on a quantum device [40].…”

“…(See the Appendix for more details on how the signature of exciton condensation, λ G was computed.) This computational signature has been utilized to study exciton condensation is possible in quantum and molecular systems [29,[38][39][40]64]. One model known to achieve a large λ G value and hence exhibit exciton condensate character in the limit of a large correlation is the Lipkin quasispin model [15][16][17][18][19][20][21].…”

Physics-Inspired Quantum Simulation of Resonating Valence Bond States─A Prototypical Template for a Spin-Liquid Ground State

“…There is also an advantage in terms of the unique parameter count (in our case, it is just 2 for each unit cell) and also auxiliary Hamiltonians with reduced number of measurables (see Auxillary Hamiltonians with Reduced Measurements section) and reduced number of shots, thereby reducing statistical error. The simplification we used for the reduction in the unique parameter count based on symmetry arguments can be adopted for other larger lattices with other symmetries depending on the topology of the lattice (for example, looks at cylindrical and torus topology out of many) and also for simulating correlated states in other problems like exciton condensates , and simultaneous Fermion-exciton condensates that has been recently realized. , …”

“…The simplification we used for the reduction in the unique parameter count based on symmetry arguments can be adopted for other larger lattices with other symmetries depending on the topology of the lattice (for example, 42 looks at cylindrical and torus topology out of many) and also for simulating correlated states in other problems like exciton condensates 56,57 and simultaneous Fermion-exciton condensates that has been recently realized. 58,59 Since our method entails preparing RVBs in real quantum devices with high fidelity, this holds significance across multiple areas of physics and chemistry, even beyond the domain of quantum spin liquids. This is because the ground-state preparation carried out in this paper would serve as a starting step for various studies one could conduct on systems that support RVBs as their ground states and be an impetus for areas in physical chemistry wherein they feature extensively.…”

Qubit Condensation for Assessing Efficacy of Molecular Simulation on Quantum Computers

“…Quantum devices have recently emerged as potentially powerful tools for the demonstration of system-wide entanglement and long-range order, − a task that can be difficult or expensive in classic computations. With an ability to simulate large degrees of quantum entanglementimportant for the modeling of many chemical processes including those involving transition-metal complexes, energetic degeneracies, solid-state materials, and other systems − quantum devices with quantum chemical algorithms are expected to compete with classical computers and methodologies for chemical computations. − …”