SARS-CoV-2 spike and ACE2 entanglement-like binding.

We describe the binding between the glycoprotein Spike of SARS-CoV-2 and the human host cell receptor ACE2 as a quantum circuit, comprising the one-qubit Hadamard quantum logic gate performing the quantum superposition of the S₁ subunit of the Spike protein, and the two-qubit quantum logic gate CNOT, which performs maximum entanglement between the Spike-qubit S₁ and the ACE2 receptor protein. Also, we consider two strategies to prevent the binding process between the Spike-qubit S₁ and the ACE2 receptor. The first one is the use of competitive peptidomimetic inhibitors that can selectively bind to the receptor binding domain (RBD) of the Spike glycoprotein with much higher affinity than the cell surface receptor itself. These inhibitors are targeted to the CNOT quantum logic gate and will get maximally entangled with the S₁ qubit in place of the natural ACE2 receptor. The second one is to use covalent inhibitors, which will destroy S₁ by acting as a projective quantum measurement. Finally, the conjecture that S₁ is a quantum bio-robot is formulated.