Parallel entangling gate operations and two-way quantum communication in spin chains

Abstract

The power of a quantum circuit is determined through the number of two-qubit entangling gates that can be performed within the coherence time of the system. In the absence of parallel quantum gate operations, this would make the quantum simulators limited to shallow circuits. Here, we propose a protocol to parallelize the implementation of two-qubit entangling gates between multiple users which are spatially separated, and use a commonly shared spin chain data-bus. Our protocol works through inducing effective interaction between each pair of qubits without disturbing the others, therefore, it increases the rate of gate operations without creating crosstalk. This is achieved by tuning the Hamiltonian parameters appropriately, described in the form of two different strategies. The tuning of the parameters makes different bilocalized eigenstates responsible for the realization of the entangling gates between different pairs of distant qubits. Remarkably, the performance of our protocol is robust against increasing the length of the data-bus and the number of users. Moreover, we show that this protocol can tolerate various types of disorders and is applicable in the context of superconductor-based systems. The proposed protocol can serve for realizing two-way quantum communication.

Long distance entanglement and high-dimensional quantum teleportation in the Fermi–Hubbard model

“…Therefore, the creation and distribution of entanglement in physical platforms is crucial in the success and implementation of quantum teleportation protocols 7 . In this context, a variety of one-dimensional quantum spin chains are known for their entangled ground states and have been intensively investigated as faithful architectures for quantum information processing [8][9][10][11][12][13][14][15] and notably as reliable quantum channels for teleportation protocols [16][17][18][19][20][21][22][23][24][25][26] . Nevertheless, in most one-dimensional quantum spin chain systems with short-range interactions, the entanglement vanishes for distances larger than two neighboring sites [27][28][29] , which makes them inconceivable platforms for long distance teleportation.…”

Quantum transfer of interacting qubits

“…However, in order to apply the same idea to achieve n-iQST, one would require a fully-engineered quantum channel, implying, in general, a modification of the couplings among the qubits embodying the sender's system. On the other hand, uniformly-coupled chains allow for high-quality n-QST for specific lengths related to prime number theory [22], and extensive research has been devoted to investigate the transfer of few-qubit entangled states over such spin chains [12][13][14][23][24][25][26]. However, a general approach to the n-QST problem has not been put forward yet, and, moreover, specific n-QST protocols may not be applicable to the n-iQST case due to the dynamical evolution of the sender's qubits.…”

Parallel Gate Operations Fidelity in a Linear Array of Flip‐Flop Qubits

“…A universal quantum computer requires indeed the capability of performing single-qubit gates and two-qubit entangling operations in parallel. [13,14] Study about quantum gate parallelism have been carried out on superconducting circuits, [15] chains of atoms, [14,[16][17][18] and spins. [13] In this work we address this kind of study on a linear array of flip-flop qubit.…”

“…[13,14] Study about quantum gate parallelism have been carried out on superconducting circuits, [15] chains of atoms, [14,[16][17][18] and spins. [13] In this work we address this kind of study on a linear array of flip-flop qubit.…”