English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Ground state preparation is classically intractable for general Hamiltonians.On quantum devices, shallow parameterized circuits can be effectively trainedto obtain short-range entangled states under the paradigm of variationalquantum eigensolver, while deep circuits are generally untrainable due to thebarren plateau phenomenon. In this Letter, we give a general lower bound on thevariance of circuit gradients for arbitrary quantum circuits composed of local2-designs. Based on our unified framework, we prove the absence of barrenplateaus in training finite local-depth circuits for the ground states of localHamiltonians. These circuits are allowed to be deep in the conventionaldefinition of circuit depth so that they can generate long-range entanglement,but their local depths are finite, i.e., there is only a finite number ofnon-commuting gates acting on individual qubits. This fact suggests thatlong-range entangled ground states, such as topologically ordered states, arein general possible to be prepared efficiently on quantum devices viavariational methods. We validate our analytical results with extensivenumerical simulations and demonstrate the effectiveness of variational trainingusing the generalized toric code model.

Absence of barren plateaus in finite local-depth circuits with long-range entanglement