Matsubara

Matsubara is a Japanese name that can refer to people, places, or scientific concepts. As a place name, Matsubara denotes a city in Osaka Prefecture, Japan, located in the Kansai region. It is part of the Osaka metropolitan area and has cultural and economic ties to nearby cities.

In physics, Matsubara frequencies are discrete imaginary frequencies used in finite-temperature quantum field theory. They arise in the imaginary-time formalism, also known as the Matsubara formalism, which replaces real time with an interval of length β = 1/(k_B T). Bosonic modes have frequencies ω_n = 2πn/β, while fermionic modes have ω_n = (2n+1)π/β, with n an integer. This framework converts integrals over energy into sums over these discrete frequencies, facilitating calculations at finite temperature.

The name Matsubara also appears as a Japanese surname and, more generally, as a toponym in various contexts. The surname Matsubara is of Japanese origin and is borne by individuals across fields such as science, sports, and the arts.