Lower-resolution interactions reduced qubits needed for deuteron energy estimates

What the study found: The study found that deuteron ground-state energy estimates on a quantum simulator became achievable with fewer harmonic oscillator basis states, and therefore fewer qubits, as the similarity renormalization group resolution scale λ was lowered. It also found that entanglement between oscillator modes decreased as λ was reduced from the bare value to about 1.0 fm−1.
Why the authors say this matters: The authors suggest that using low-resolution effective interactions can make quantum-simulator calculations of the deuteron more resource-efficient. They also indicate that the observed reduction in entanglement helps explain the reduced computational requirements.
What the researchers tested: The researchers used the variational quantum eigensolver, a quantum algorithm for estimating ground-state energies, on the Qiskit-Aer simulator. They tested realistic two-body nuclear interactions, specifically chiral N4LO and AV18, evolved them to lower resolution scales with the similarity renormalization group, and examined both noise-free and noisy cases using noise models taken from IBM quantum hardware.
What worked and what didn't: The deuteron ground-state energy was calculated in a truncated harmonic oscillator basis, and the number of basis states needed to reach within 1% of the experimental value decreased as λ decreased. The noisy results were extrapolated to the zero-noise limit. The entanglement analysis showed a decrease in concurrence, an entanglement measure, as λ was lowered, independent of the bare interaction form and the number of basis states.
What to keep in mind: The abstract does not describe detailed numerical values beyond the 1% target and the approximate λ range. It also does not provide additional limitations beyond the use of a truncated basis and simulator-based, noise-modeled calculations.

Key points

• Lowering the similarity renormalization group scale λ reduced the number of harmonic oscillator basis states needed for deuteron energy estimates.
• The calculations used the variational quantum eigensolver on the Qiskit-Aer simulator.
• Two realistic nuclear interactions were tested: chiral N4LO and AV18.
• Noise models were taken from IBM quantum hardware, and noisy results were extrapolated to zero noise.
• Concurrence, an entanglement measure, decreased as λ was lowered to about 1.0 fm−1.