Find in Library
Search millions of books, articles, and more
Indexed Open Access Databases
From the Jordan Product to Riemannian Geometries on Classical and Quantum States
oleh: Florio M. Ciaglia, Jürgen Jost, Lorenz Schwachhöfer
Format: | Article |
---|---|
Diterbitkan: | MDPI AG 2020-06-01 |
Deskripsi
The Jordan product on the self-adjoint part of a finite-dimensional <inline-formula> <math display="inline"> <semantics> <msup> <mi>C</mi> <mo>*</mo> </msup> </semantics> </math> </inline-formula>-algebra <inline-formula> <math display="inline"> <semantics> <mi mathvariant="script">A</mi> </semantics> </math> </inline-formula> is shown to give rise to Riemannian metric tensors on suitable manifolds of states on <inline-formula> <math display="inline"> <semantics> <mi mathvariant="script">A</mi> </semantics> </math> </inline-formula>, and the covariant derivative, the geodesics, the Riemann tensor, and the sectional curvature of all these metric tensors are explicitly computed. In particular, it is proved that the Fisher–Rao metric tensor is recovered in the Abelian case, that the Fubini–Study metric tensor is recovered when we consider pure states on the algebra <inline-formula> <math display="inline"> <semantics> <mrow> <mi mathvariant="script">B</mi> <mo>(</mo> <mi mathvariant="script">H</mi> <mo>)</mo> </mrow> </semantics> </math> </inline-formula> of linear operators on a finite-dimensional Hilbert space <inline-formula> <math display="inline"> <semantics> <mi mathvariant="script">H</mi> </semantics> </math> </inline-formula>, and that the Bures–Helstrom metric tensors is recovered when we consider faithful states on <inline-formula> <math display="inline"> <semantics> <mrow> <mi mathvariant="script">B</mi> <mo>(</mo> <mi mathvariant="script">H</mi> <mo>)</mo> </mrow> </semantics> </math> </inline-formula>. Moreover, an alternative derivation of these Riemannian metric tensors in terms of the GNS construction associated to a state is presented. In the case of pure and faithful states on <inline-formula> <math display="inline"> <semantics> <mrow> <mi mathvariant="script">B</mi> <mo>(</mo> <mi mathvariant="script">H</mi> <mo>)</mo> </mrow> </semantics> </math> </inline-formula>, this alternative geometrical description clarifies the analogy between the Fubini–Study and the Bures–Helstrom metric tensor.