Format code and add changelog

Author: albertomercurio

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/qutip/QuantumToolbox.jl/tree/main)
 
+- Improve efficiency of `bloch_redfield_tensor` by avoiding unnecessary conversions. ([#509])
+
 ## [v0.33.0]
 Release date: 2025-07-22
 
@@ -267,3 +269,4 @@ Release date: 2024-11-13
 [#504]: https://github.com/qutip/QuantumToolbox.jl/issues/504
 [#506]: https://github.com/qutip/QuantumToolbox.jl/issues/506
 [#507]: https://github.com/qutip/QuantumToolbox.jl/issues/507
+[#509]: https://github.com/qutip/QuantumToolbox.jl/issues/509

test/core-test/brmesolve.jl

@@ -5,8 +5,9 @@
     A_op = a+a'
     spectra(x) = (x>0) * 0.5
     for sec_cutoff in [0, 0.1, 1, 3, -1]
-        R = bloch_redfield_tensor(H, ((A_op, spectra), ), [a^2], sec_cutoff = sec_cutoff, fock_basis = Val(true))
-        R_eig, evecs = bloch_redfield_tensor(H, ((A_op, spectra), ), [a^2], sec_cutoff = sec_cutoff, fock_basis = Val(false))
+        R = bloch_redfield_tensor(H, ((A_op, spectra),), [a^2], sec_cutoff = sec_cutoff, fock_basis = Val(true))
+        R_eig, evecs =
+            bloch_redfield_tensor(H, ((A_op, spectra),), [a^2], sec_cutoff = sec_cutoff, fock_basis = Val(false))
         @test isa(R, QuantumObject)
         @test isa(R_eig, QuantumObject)
         @test isa(evecs, QuantumObject)