add qeye_like

Author: cailixun

.github/workflows/CI.yml

@@ -56,11 +56,11 @@ jobs:
 
         include:
           # for core tests (intermediate versions)
-          # - version: '1.x'
-          #   node:
-          #     os: 'ubuntu-latest'
-          #     arch: 'x64'
-          #   group: 'Core'
+          - version: '1.11'
+            node:
+              os: 'ubuntu-latest'
+              arch: 'x64'
+            group: 'Core'
 
           # for extension tests
           - version: '1'

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased](https://github.com/qutip/QuantumToolbox.jl/tree/main)
 
 - Fix `cite()` bibtex output. ([#552])
+- Add `qeye_like`, which is a synonym of `one`. ([#555])
 
 ## [v0.36.0]
 Release date: 2025-09-29
@@ -326,3 +327,4 @@ Release date: 2024-11-13
 [#544]: https://github.com/qutip/QuantumToolbox.jl/issues/544
 [#546]: https://github.com/qutip/QuantumToolbox.jl/issues/546
 [#552]: https://github.com/qutip/QuantumToolbox.jl/issues/552
+[#555]: https://github.com/qutip/QuantumToolbox.jl/issues/555

docs/src/resources/api.md

@@ -188,6 +188,7 @@ logm
 expm
 sinm
 cosm
+qeye_like
 ```
 
 ## [Time evolution](@id doc-API:Time-evolution)

docs/src/users_guide/QuantumObject/QuantumObject_functions.md

@@ -11,7 +11,7 @@ Here is a table that summarizes all the supported linear algebra functions and a
 | **Description** | **Function call** | **Synonyms** |
 |:----------------|:------------------|:-------------|
 | zero-like array | [`zero(Q)`](@ref zero) | - |
-| identity-like matrix | [`one(Q)`](@ref one) | - |
+| identity-like matrix | [`one(Q)`](@ref one) | [`qeye_like(Q)`](@ref qeye_like) |
 | conjugate | [`conj(Q)`](@ref conj) | - |
 | transpose | [`transpose(Q)`](@ref transpose) | [`trans(Q)`](@ref trans) |
 | conjugate transposition | [`adjoint(Q)`](@ref adjoint) | [`Q'`](@ref adjoint), [`dag(Q)`](@ref dag) |

src/qobj/synonyms.jl

@@ -5,7 +5,7 @@ Synonyms of the functions for QuantumObject
 export Qobj, QobjEvo, shape, isherm
 export trans, dag, matrix_element, unit
 export tensor, ⊗
-export qeye
+export qeye, qeye_like
 export vector_to_operator, operator_to_vector
 export sqrtm, logm, expm, sinm, cosm
 
@@ -104,3 +104,12 @@ Matrix cosine of [`QuantumObject`](@ref), defined as
 Note that this function is same as `cos(A)` and only supports for [`Operator`](@ref) and [`SuperOperator`](@ref).
 """
 cosm(A::QuantumObject{ObjType}) where {ObjType<:Union{Operator,SuperOperator}} = cos(A)
+
+@doc raw"""
+    qeye_like(A::AbstractQuantumObject)
+
+Return a similar [`AbstractQuantumObject`](@ref) with `dims` and `type` are same as `A`, but `data` is an identity matrix.
+
+Note that this function is same as `one(A)` and only supports for [`Operator`](@ref) and [`SuperOperator`](@ref).
+"""
+qeye_like(A::AbstractQuantumObject{OpType}) where {OpType<:Union{Operator,SuperOperator}} = one(A)

test/core-test/quantum_objects.jl

@@ -203,7 +203,7 @@
         @test a2 * 2 == 2 * a2
 
         zero_like = zero(a2)
-        iden_like = one(a3)
+        iden_like = qeye_like(a3)
         zero_array = spzeros(ComplexF64, 100, 100)
         iden_array = sparse(1:100, 1:100, ones(ComplexF64, 100))
         @test zero_like == Qobj(zero_array, type = a2.type, dims = a2.dims)