Unitary-projective entanglement dynamics

Starting from a state of low quantum entanglement, local unitary time evolution increases the entanglement of a quantum many-body system. In contrast, local projective measurements disentangle degrees of freedom and decrease entanglement. We study the interplay of these competing tendencies by considering time evolution combining both unitary and projective dynamics. We begin by constructing a toy model of Bell pair dynamics which demonstrates that measurements can keep a system in a state of low, i.e., area-law, entanglement, in contrast with the volume-law entanglement produced by generic pure unitary time evolution. While the simplest Bell pair model has area-law entanglement for any measurement rate, as…

• NS
  National Science Foundation

  Awards: 1734006, DMR-13001648
• SV
  Silicon Valley Community Foundation
• FQ
  Foundational Questions Institute

  Award: FQXi-RFP-1617
• PC
  Presbyterian College and Theological Seminary
• EA
  Engineering and Physical Sciences Research Council

  Awards: EP/N01930X/1, EP/S020527/1, EP/N01930X/1
• KI
  Kavli Institute for Theoretical Physics, University of California, Santa Barbara