We systematically study the construction of mutually unbiased bases in C 2 C 3 , such that all the bases are unextendible maximally entangled ones. Necessary conditions of constructing a pair of mutually unbiased unextendible maximally entangled bases in C 2 C 3 are derived. Explicit examples are presented.
Keywords Mutually unbiased bases · Unextendible maximally entangled bases · Quantum entanglementMutually unbiased bases (MUBs) play important roles in many quantum information processing such as quantum state tomography [1-3], cryptographic protocols [4][5][6][7][8][9], and the mean kings problem [10]. They are also useful in the construction of generalized Bell states. Let B 1 = {|φ i } and B 2 = {|ψ i }, i = 1, 2, · · · , d, be two orthonormal bases of a ddimensional complex vector space C d , φ j |φ i = δ ij , ψ j |ψ i = δ ij . B 1 and B 2 are said to be mutually unbiased if and only ifPhysically if a system is prepared in an eigenstate of basis B 1 and is measured in basis B 2 , then all the measurement outcomes have the same probability.A set of orthonormal bases {B 1 , B 2 , ..., B m } in C d is called a set of MUBs if every pair of bases in the set is mutually unbiased. For given dimension d, the maximum number of MUBs is no more than d + 1. It has been shown that there are d + 1 MUBs when d is a prime power [1,11,12]. However, for general d, e.g. d = 6, it is a formidable problem to determine the maximal numbers of MUBs [13][14][15][16][17][18][19][20][21].