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- Types of photon qubit encoding 2 answers
Usually in quantum optics, one uses the polarization degree of freedom of the photon to create and manipulate photonic qubits. This, using various linear optics devices, can be coupled with the 'path degree of freedom' inside an interferometer for instance. So far, that makes two 'available' degrees of freedom to store quantum information as qubits.
But what else can we use in photons ? One can immediately discard the angular momentum degree of freedom, since this is just the left or right circular polarization state.
Maybe the wavelength ? But how could it be used, ie how could you create and manipulate quantum superpositions of wavelength states ?
I try to think of others, but I quite lack of imagination and experience in this field.
Thanks in advance,