IBM Quantum Hardware Simulates 100-Site Spin Chain with Near-Perfect Fidelity

Researchers at IBM have made significant strides in quantum simulation by successfully preparing and analyzing a 100-site spin chain on their quantum hardware. The team achieved high fidelity, with results ranging from 97.9 to 99.0 percent, when compared to density matrix renormalisation group (DMRG) algorithm results.

The IBM researchers used tensor-network-based approximate quantum compiling protocol to construct shallow circuits, which enabled the preparation of the 100-site ground states. These circuits had a depth of only 18-39 CNOT gates, allowing for accurate results without excessive entanglement.

The team directly measured string order for lengths up to 20 sites, providing strong evidence for the presence of symmetry-protected topological (SPT) order. This was achieved by observing entanglement spectrum degeneracies and detecting symmetry-protected edge modes.