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.
Highlights
In order to achieve universal computation on a digital quantum simulator one requires the capability of performing arbitrary local single-qubit unitary rotations on every qubit as well as one type of two-qubit entangling gate between any pair of qubits [7]
In order to be universal quantum computers, digital quantum simulators require the capability of performing single-qubit gates and two-qubit entangling operations
While the implementation of single-qubit gates relies on the capability of controlling individual particles and performing local unitary operations, the fulfillment of two-qubit entangling gates demands direct interaction between qubits which makes it more challenging, between distant qubits
Summary
In order to achieve universal computation on a digital quantum simulator one requires the capability of performing arbitrary local single-qubit unitary rotations on every qubit as well as one type of two-qubit entangling gate between any pair of qubits [7]. To achieve parallel gate operation, we create an effective interaction between each pair of users through properly tuning the Hamiltonian parameters. Throughout the paper a pretty long chain of size N =30 the gate fidelity and for both strategies, we fix a time window, for F max still exceeds 0.92 This shows the high-quality the dynamics of the system and maximize the performance of parallel gate operation between two average gate fidelity F with respect to the Hamilto- pairs of users. In large chains nian parameters to find their optimal values, namely J0opt/J , ho0pt/J and hoνpt/J , by brute-force optimizathe first strategy offers better performance over the second one in terms of the gate fidelity. The first strategy presents better performance than the other one for long chains
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