December 9, 2022

New quantum algorithm surpasses the famous Quantum Phase Estimation

New quantum algorithm surpasses the famous Quantum Phase Estimation Comparison of the new quantum circuit with our previous one Credit: Kenji Sugisaki, Takeji Takui, Kazunobu Sato

A team of researchers at Osaka City University has developed a quantum algorithm they called Bayesian eXchange coupling parameter calculator with Broken-symmetry wave functions (BxB), that predicts the electronic states of atoms and molecules by directly calculating the energy differences. They noted that energy differences in atoms and molecules remain constant, regardless to how complex and large they get despite their total energies grow as the system size.

Using the computing costs of a well-known algorithm called Quantum Phase Estimation (QPE) as a benchmark, they calculated the vertical ionization energies of small molecules such as CO, O2, CN, F2, H2O, NH3 within 0.1 electron volts (eV) of precision, using half the number of qubits, bringing the calculation cost on par with QPE.

The researchers are expecting the BxB quantum algorithm to perform high-precision energy calculations for large molecules that cannot be treated in real time with conventional computers. (

The paper has been published in the Journal of Physical Chemistry Letters.

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