The Peierls distorted chain as a quantum data bus for quantum state transfer

Abstract

We systematically study the transfer of quantum state of electron spin as the flying qubit along a half-filled Peierls distorted tight-binding chain described by the Su-Schrieffer-Heeger (SSH) model, which behaves as a quantum data bus. This enables a novel physical mechanism for quantum communication with always-on interaction: the effective hopping of the spin carrier between sites A and B connected to two sites in this SSH chain can be induced by the quasi-excitations of the SSH model. As we prove, it is the Peierls energy gap of the SSH quasi-excitations that plays a crucial role to protect the robustness of the quantum state transfer process. Moreover, our observation also indicates that such a scheme can also be employed to explore the intrinsic property of the quantum system.

Disorder-assisted distribution of entanglement in XY spin chains

“…A quite straightforward way to compute the entanglement between both partitions A and B, given that the overall state is pure, is through the well-known von Neumann entropy (6) which in our case is bounded by the interval [0, 1], with 0 accounting for a product (separable) state and 1 for a fully-entangled one. The entropy above thus depends only on the total probability p of finding the excitation within block A L , reaching its maximum when p = 1/2.…”

“…Following that, it has been shown that low-dimensional spin chains can act as efficient (especially for short-distance communication) quantum "wires" for carrying out quantum-state transfer protocols [1][2][3][4][5][6][7][8][9][10][11] as well as creation and distribution of entanglement [12][13][14][15][16][17][18][19][20][21], both being pivotal tasks in quantum networks [22]. Physically, spin chains may be implemented in many platforms such as NMR systems [23], optical lattices [24,25], arrays of coupled cavity-QED systems [26,27], superconducting circuits [28], nitrogen vacancies in diamond [29], and waveguides [30].…”

Resonant atom-field interaction in large-size coupled-cavity arrays

“…In this work we have restricted to the case of odd N. Indeed, in our staggered tight-binding model with open BCs the even and odd cases cannot be treated on the same footing like with cyclic conditions [19]. In the even case, while major features such as the presence of a band gap with a discrete level at its center still hold the discrete level, when present, becomes twofold [21].…”

“…Here, the bound mode responsible for the phenomena that we have presented arises in a somewhat different way since no impurities or defects are present. Rather, its emergence is essentially a pure boundary effect stemming solely from the finiteness of the array length (we recall that under cyclic BCs this mode is absent [19]). As such, aside from the specific context here addressed the present work provides a paradigmatic example of boundary effects in a CCAs scenario.…”

Quantum-state transfer in staggered coupled-cavity arrays

“…The above bilocalization effect is usually achieved by introducing perturbation terms in the Hamiltonian that decouple the outermost spins from the bulk. This can be realized (i) by applying strong local magnetic fields on the edge spins [48,58], (ii) by applying such fields on their nearest-neighbors [49], and (iii) by engineering weak couplings between the edge spins and the bulk [46,52]. While all these models share that a pair of Hamiltonian eigenstates exhibits strong bilocalizaton at the edge sites, the typical energy gap between such two states-and, accordingly, the transmission time-depend on the considered model.…”