3 papers
cond-mat.stat-mech2020
Thermodynamics at zero temperature: inequalities for the ground state of a quantum many-body system
N. Il'in, E. Shpagina, O. Lychkovskiy
We prove that for a single-component many-body system at zero temperature the inequality holds, where is the interaction energy, is pres…
quant-ph2018
Merits of using density matrices instead of wave functions in the stationary Schrödinger equation for systems with symmetries
E. Shpagina, F. Uskov, N. Il'in +1
The stationary Schrödinger equation can be cast in the form , where is the system's Hamiltonian and is the system's density matrix. We explore the merits of this…
quant-ph2017
Squaring parametrization of constrained and unconstrained sets of quantum states
N. Il'in, E. Shpagina, F. Uskov +1
A mixed quantum state is represented by a Hermitian positive semi-definite operator with unit trace. The positivity requirement is responsible for a highly nontrivial geometry…