Experimental verification of the commutation relation for Pauli spin operators using single-photon quantum interference

We report experimental verification of the commutation relation for Pauli spin operators using quantum interference of the single-photon polarization state. By superposing the quantum operations $\sigma_z \sigma_x$ and $\sigma_x \sigma_z$ on a single-photon polarization state, we have experimentally implemented the commutator, $[\sigma_{z}, \sigma_{x}]$, and the anticommutator, $\{\sigma_{z}, \sigma_{x}\}$, and have demonstrated the relative phase factor of $\pi$ between $\sigma_z \sigma_x$ and $\sigma_x \sigma_z$ operations. The experimental quantum operation corresponding to the commutator, $[\sigma_{z}, \sigma_{x}]=k\sigma_y$, showed process fidelity of 0.94 compared to the ideal $\sigma_y$ operation and $|k|$ is determined to be $2.12\pm0.18$.Comment: 4pages, 3 figure

Realizing Physical Approximation of the Partial Transpose

The partial transpose by which a subsystem's quantum state is solely transposed is of unique importance in quantum information processing from both fundamental and practical point of view. In this work, we present a practical scheme to realize a physical approximation to the partial transpose using local measurements on individual quantum systems and classical communication. We then report its linear optical realization and show that the scheme works with no dependence on local basis of given quantum states. A proof-of-principle demonstration of entanglement detection using the physical approximation of the partial transpose is also reported.Comment: 5 pages with appendix, 3 figure

I Am Fine but You Are Not: Optimistic Bias and Illusion of Control on Information Security

Information security is a critically important issue in current networked business and work environments. While there is extensive publicity on the increasing incidents of numerous information security breaches and their serious consequences, recent surveys and research on information security repeatedly identify the low levels of user and managerial awareness as a key obstacle to achieving a good information security posture. The main motivation of our research emanates from this contradicting phenomenon: increased vulnerability to information security breaches yet the low level of user and managerial awareness on information security threats. In this research, we study this dissonance by addressing a cognitive bias, optimistic bias, that is, the tendency of people to believe that negative events are less likely to happen to them than to others and that positive events are more likely to happen to them than others. Using a survey, we find that users demonstrate optimistic bias in their risk perceptions associated with information security. This self-serving bias is also found to be related to a perception of controllability with information security threats. These results have practical implications for designing security awareness programs by suggesting that risk communication and management efforts are likely to fail unless they consider this bias

Experimental Implementation of the Universal Transpose Operation

The universal transpose of quantum states is an anti-unitary transformation that is not allowed in quantum theory. In this work, we investigate approximating the universal transpose of quantum states of two-level systems (qubits) using the method known as the structural physical approximation to positive maps. We also report its experimental implementation in linear optics. The scheme is optimal in that the maximal fidelity is attained and also practical as measurement and preparation of quantum states that are experimentally feasible within current technologies are solely applied.Comment: 4 pages, 4 figure