Detecting entanglement can be more effective with inequivalent mutually unbiased bases

Mutually unbiased bases (MUBs) provide a standard tool in the verification of quantum states, especially when harnessing a complete set for optimal quantum state tomography. In this work, we investigate the detection of entanglement via inequivalent sets of MUBs, with a particular focus on unextendible MUBs. These are bases for which an additional unbiased basis cannot be constructed and, consequently, are unsuitable for quantum state verification. Here, we show that unextendible MUBs, as well as other inequivalent sets in higher dimensions, can be more effective in the verification of entanglement. Furthermore, we provide an efficient and systematic method to search for inequivalent MUBs and show that such sets occur regularly within the Heisenberg-Weyl MUBs, as the dimension increases. Our findings are particularly useful for experimentalists since they demonstrate that a clever selection of MUBs allows for entanglement detection with fewer measurements.

Automated summary

In this study, the detection of entanglement using inequivalent sets of MUBs, including unextendible MUBs, was explored, showing that such sets can be more effective in entanglement verification. An efficient method to search for inequivalent MUBs was provided, with a regular occurrence of such sets within the Heisenberg-Weyl MUBs as dimension increases. The findings suggest that a clever selection of MUBs can lead to entanglement detection with fewer measurements, which is particularly useful for experimentalists.