Researchers simulate bosonic tunneling on IBM and IonQ processors with 200-gate circuits
A preprint compares binary and unary encodings for simulating bosonic position dynamics on IBM and IonQ quantum processors. Short unary circuits reproduced tunneling in a double-well benchmark, while deeper binary product-formula circuits failed. The result matters because encoding and compilation choices may let current noisy quantum devices tackle small physical simulations that are hard to run classically.
A team posted an arXiv preprint comparing two ways to encode a single bosonic position degree of freedom on IBM superconducting and IonQ trapped-ion processors. The authors simulated real-time dynamics in a symmetric double well, using binary encoding with quantum Fourier transform circuits and unary encoding with one qubit per lattice site. The headline result came from unary circuits containing about two hundred two-qubit gates.
On IBM, the probability in the initially occupied right well fell from 0.97 to 0.06, indicating tunneling to the left well. On IonQ, the right-well probability fell from 0.96 to 0.12. The authors said binary product-formula circuits with several thousand two-qubit gates did not reproduce the transfer. Noiseless emulation showed the difference depended on compilation as well as encoding: without a fixed-size optimization, a unary product formula also needed several thousand gates.
The result matters because qubit hardware does not naturally hold continuous bosonic position; choosing an encoding shapes circuit depth. Unary encoding treats the lattice like a chain of sites, letting excitation-conserving gates move probability locally. Binary encoding compresses positions into qubits but needs Fourier transforms and deeper gates. For the single-degree-of-freedom problem, the unary circuit maps to a free-fermion problem and compresses exactly. Coupled-oscillator benchmarks showed the best encoding depends on grid size and evolution time, so no universal winner.
The study design is a computational benchmark on two hardware platforms, with the main unary circuits using about two hundred two-qubit gates; the key limitation is that the sample is small and not a broad quantum-advantage claim. The practical stakes are for quantum computing's transition from demonstrations to utility. If noisy devices can resolve tunneling with shorter, better-compiled circuits, researchers can test materials, chemistry, and many-body physics models that classical simulation struggles with. The preprint shows encoding and compiler choices can make otherwise fragile simulations feasible on current processors.
The work affects quantum computing researchers and hardware users because it shows how encoding and compiler choices can make small bosonic simulations feasible on current noisy machines. It is a step toward practical utility, not a broad advantage claim.
Sources (1)
- [1]Quantum simulation of real-time bosonic dynamics with binary and unary position encodings on superconducting and trapped-ion processors(https://arxiv.org/abs/2611.13079)