2-unitary matrix $U_{36}$
S. Rather, A. Burchardt, W. Bruzda, G. Rajchel-Mieldzioć, A. Lakshminarayan and K. Życzkowski
Under construction
with maximal entangling power, implying existence of absolutely maximally entangled states $AME(4,6)$ of four subsystems with six levels each, a perfect tensor $T_{ijkl}$ with four indices, each running from one to six and quantum, and quantum error correction codes: pure code $((4,1,3 ))_ 6$ and shortened code $((3,6,2))_ 6$, which allows encoding a 6-level state into a set of three such subsystems.
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