Patent ID: 8620166

Claim:
An optical receiver comprising: a unitary transformation operator to: receive an n-symbol optical codeword associated with a codebook, the n-symbol optical codeword being based on a Hadamard matrix, and perform a unitary transformation on the received optical codeword to generate a transformed optical codeword, the unitary transformation being based on the codebook, and the unitary transformation operator including n*log 2 (n/2) beamsplitters; n optical detectors including n single photon detectors, a particular one of the n optical detectors being to: detect a particular optical symbol of the transformed optical codeword, and determine whether the particular optical symbol corresponds to at least a first optical symbol or a second optical symbol; and a decoder to: construct a codeword based on determining whether the particular optical symbol corresponds to the at least the first optical symbol or the second optical symbol, and decode the constructed codeword into a message using the codebook.