Magnetic bilayer qubits: A bipartite quantum system

An exfoliated monolayer CrI possessing the ferromagnetic (FM) nature of out-of-plane Ising spin-up (or spin-down) electrons can be considered as a qubit with a quantum state of |>=|↑>=|0> (or |>=|↓>=|1>) due to the theory of the Bloch sphere. Therefore, here a bipartite quantum system of the antiferromagnetic (AFM) and FM bilayer CrI is proposed for four fundamental two-qubit (2Q) quantum states (≡|>) of |↑↓>=|01>, |↓↑>=|10>, |↑↑>=|00> and |↓↓>=|11>, respectively. Energy-resolved magnetic circular dichroism (MCD) spectropolarimetry was used to detect - transitions of the FM and AFM bilayer CrI for the four fundamental quantum states. The obtained MCD spectra of the - transitions with spin-frustration and spin-parallelism possess quantum signals of the four fundamental 2Q quantum states at = 0, where is the angle between the magnetic field and the surface normal. Hence, the bilayer CrI is a potential candidate for use in quatum computer.