New Method of Obtaining the Kochen-Specker Theorem

Adán Cabello, JoséM. Estebaranz, Guillermo García Alcaine

Asher Peres

Mordecai Waegell, P. K. Aravind

A Kochen-Specker (KS) set is a specific set of projectors and measurement contexts that prove the Bell-Kochen-Specker contextuality theorem. The simplest known KS sets in Hilbert space dimensions $d=3,4,5,6,8$ are reproduced, and several methods by which a new KS set can be constructed using one or more known KS sets in lower dimensions are reviewed and improved. These KS sets and improved methods enable the construction of explicitly critical new KS sets in all dimensions, where critical refers to the irreducibility of the set of contexts. The simplest known critical KS sets are derived in all even dimensions $d\ensuremath{\ge}10$ with at most nine contexts and 30 projectors, and in all odd dimensions $d\ensuremath{\ge}7$ with at most 13 contexts and 39 projectors. These results show that neither the number of contexts nor the number of projectors in a minimal KS set scales with dimension $d$.

Zhengyu Li, Curtis Bright, Vijay Ganesh

Abstract One of the most fundamental results in the foundations of quantum mechanics is the Kochen--Specker (KS) theorem, a `no-go' theorem which states that contextuality is an essential feature of any hidden-variable theory. The theorem hinges on the existence of a mathematical object called a KS vector system. Although the existence of a KS vector system was first established by Kochen and Specker, the problem of the minimum size of such a system has stubbornly remained open for over 50 years. In this paper, we present a new method based on a combination of a SAT solver and a computer algebra system (CAS) to address this problem. We improve the lower bound on the minimum number of vectors in a KS system from 22 to 23 and improve the efficiency of the search by a factor of over 1000 when compared to the most recent computational methods. Finding a minimum KS system would simplify experimental tests of the KS theorem and have direct applications in quantum information processing, specifically in the security of quantum cryptographic protocols based on complementarity, zero-error classical communication, and dimension witnessing.

Cecilia Flori

Ravi Kunjwal, Robert W. Spekkens

A generalized principle of noncontextuality applicable to noisy experimental data is discussed. An approach to obtaining noise-robust noncontextuality inequalities starting from arbitrary statistical proofs of the Kochen-Specker theorem is presented.