We consider the local unitary equivalence of a class of quantum states in bipartite case and multipartite case. The necessary and sufficient condition is presented. As special cases, the local unitary equivalent classes of isotropic state and werner state are provided. Then we study the local unitary similar equivalence of this class of quantum states and analyze the necessary and sufficient condition.
The CANDECOMP/PARAFAC (CP) decomposition is a generalization of the spectral decomposition of matrices to higher-order tensors. In this paper we use the CP decomposition to study unitary equivalence of higher order tensors and construct several invariants of local unitary equivalence for general higher order tensors. Based on this new method, we study the coefficient tensors of $3$-qubit states and obtain a necessary and sufficient criterion for local unitary equivalence of general tripartite states in terms of the CP decomposition. We also generalize this method to obtain some invariants of l…
Characterizing local unitary equivalence of multipartite states by local unitary Bargmann invariants
School of Mathematics and Data Science, Jiangnan University(江南大学数学与数据科学学院);School of Mathematical Sciences, Beihang University(北京航空航天大学数学科学学院);School of Mathematical Sciences, Capital Normal University(首都师范大学数学科学学院)
Local unitary equivalence and entanglement of multipartite pure states
在[B]中给出了任意n比特纯量子态在局域幺正(LU)运算下等价的充要条件。Kraus Phys. Rev. Lett. 104,020504(2010)]用于确定多达五个量子比特状态的不同LU等价类。由于这种分类,发现了表征多体纠缠的新参数,并给出了它们的物理解释。此外,我们还用这种方法导出了两个n比特态(n>2)的例子,它们具有任意子系统的熵都一致的性质,但它们既不是LU等价的,也不能通过一般的局域操作和经典通信相互映射.
This study investigates the unitary equivalence of split-step quantum walks (SSQW). We consider a new class of quantum walks which includes all SSQWs. We show the explicit form of quantum walks in this class, and clarify their unitary equivalence classes. Unitary equivalence classes of Suzuki's SSQW are also given.
Local unitary versus local Clifford equivalence of stabilizer and graph states
局域变换下稳定态的等价性对于理解纠缠的性质和应用具有重要意义。两个稳定器状态在通常的随机局部操作和经典通信准则下是等价的当且仅当它们在局部酉(LU)操作下是等价的。更令人惊讶的是,在某些条件下,两个LU等效稳定子状态在局部Clifford(LC)操作下也是等效的,如Van den Nest等人[\textbf{A71},062323]所示。在这里,我们扩大了一类的稳定状态的LU等价意味着LC等价($LU\Leftrightarrow LC$),包括所有的稳定状态表示的图既没有周期的长度为3或4。与Van den Nest等的结果进行比较。的条件下,我们证明了任何距离为$δ=2$的稳定态都超出了他们的判据。然后,我们进一步证明了$LU\Leftrightarrow LC$适用于$δ=2$的更一般类别的稳定态。我们还明确地构建图形表示$δ>2$稳定剂状态,超出了他们的标准:我们确定所有58个图形与多达11个顶点,并构建图形与$2^m-1$($m\geq 4$)顶点使用量子纠错码具有非Clifford横向门。
We analytically study quantum dissipative dynamics described by the Caldirola-Kanai model with inter-particle interactions. We have found that the dissipative quantum dynamics of the Caldirola-Kanai model can be exactly mapped to a dissipationless quantum dynamics under a negative external harmonic potential, even when the particles are strongly interacting. In particular, we show that the mapping is valid for the unitary Fermi gas, which is relevant for cold atoms and nuclear matters.
We study the equivalence of mixed states under local unitary transformations. First we express quantum states in Bloch representation. Then based on the coefficient matrices, some invariants are constructed. This method and results can be extended to multipartite high dimensional system.
Complex phase factors are viewed not only as redundancies of the quantum formalism but instead as remnants of unitary transformations under which the probabilistic properties of observables are invariant. It is postulated that a quantum observable corresponds to a unitary representation of an abelian Lie group, the irreducible subrepresentations of which correspond to the observable's outcomes. It is shown that this identification agrees with the conventional identification as self-adjoint operators. The upshot of this formalism is that one may 'second quantize' the representation to which an …