In this paper we discuss a model of quantum computer in which a state is an operator of density matrix and gates are general quantum operations, not necessarily unitary. A mixed state (operator of density matrix) of n two-level quantum systems is considered as an element of 4n-dimensional operator Hilbert space (Liouville space). It allows to use a quantum computer model with four-valued logic....

The design of a four-dimensional toric code is explored with the goal finding lattice capable implementing logical $\mathsf{CCCZ}$ gate transversally. established octaplex tessellation, which regular tessellation Euclidean space whose underlying 4-cell octaplex, or hyper-diamond. This differs from conventional 4D lattice, based on hypercubic symmetric respect to $X$ and $Z$ only allows for impl...

introduction: the aim of this study was to compare the effect of post space preparation with gates glidden drills or hand files on the sealing ability of gutta-percha or resilon obturation materials. materials and methods: one-hundred and four single-rooted human teeth were instrumented and divided into four experimental groups (n=21 each) and two groups of positive and negative control (n=10)....

Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions of qubit systems, we investigate the possibility of ququart systems (four-dimensional states) dependent on two DOFs of photon systems. We propose some useful one-parameter four-dimensional quantum transformations for the construction of universal ququart logic gates. The interface ...

In this paper we generalize the usual model of quantum computer to a model in which the state is an operator of density matrix and the gates are general superoperators (quantum operations), not necessarily unitary. A mixed state (operator of density matrix) of n twolevel quantum system (open or closed n-qubit system) is considered as an element of 4dimensional operator Hilbert space (Liouville ...

Shaker potassium channels from Drosophila are composed of four identical subunits. The contribution of a single subunit to the inactivation gating transition was investigated. Channels carrying a specific mutation in a single subunit can be labeled in a heterogeneous population and studied quantitatively with scorpion toxin sensitivity as a selection tag. Linkage within a single subunit of a mu...

The controlled-not gate and the single qubit gates are considered elementary gates in quantum computing. It is natural to ask how many such elementary gates are needed to implement more elaborate gates or circuits. Recall that a controlled-U gate can be realized with two controlled-not gates and four single qubit gates. We prove that this implementation is optimal if and only if the matrix U sa...