Maximum Information and Quantum Prediction Algorithms

Optimum detection for extracting maximum information from symmetric qubit sets

We demonstrate a class of optimum detection strategies for extracting the maximum information from sets of equiprobable real symmetric qubit states of a single photon. These optimum strategies have been predicted by Sasaki et al. [Phys. Rev. A{\bf 59}, 3325 (1999)]. The peculiar aspect is that the detections with at least three outputs suffice for optimum extraction of information regardless of the number of signal elements. The cases of ternary (or trine), quinary, and septenary polarization signals are studied where a standard von Neumann detection (a projection onto a binary orthogonal basi…

Constructing valid density matrices on an NMR quantum information processor via maximum likelihood estimation

Estimation of quantum states is one of the most important steps in any quantum information processing experiment. A naive reconstruction of the density matrix from experimental measurements can often give density matrices which are not positive, and hence not physically acceptable. How do we ensure that at all stages of reconstruction, we keep the density matrix positive and normalized? Recently a method has been suggested based on maximum likelihood estimation, wherein the density matrix is guaranteed to be positive definite. We experimentally implement this protocol and demonstrate its utili…

Experimental Realization of Maximum Confidence State Discrimination for the Extraction of Quantum Information

We present the first experimental demonstration of the maximum confidence measurement strategy for quantum state discrimination. Applying this strategy to an arbitrary set of states assigns to each input state a measurement outcome which, when realized, gives the highest possible confidence that the state was indeed present. The theoretically optimal measurement for discriminating between three equiprobable symmetric qubit states is implemented in a polarization-based free-space interferometer. The maximum confidence in the measurement result is 2/3. This is the first explicit demonstration th…

从对称态的受损副本中检索最大信息

Retrieving maximum information of symmetric states from their corrupted copies

针对噪声导致对称态结构畸变的问题，本文借助量子计量学与半定规划刻画最优测量，并对群协变噪声给出显式方案，以从受损副本中检索最大信息。

Carnot 量子信息引擎在最大功率下的效率

Efficiency at maximum power of a Carnot quantum information engine

本文针对量子信息引擎，提出了广义有限时间Carnot循环，在低耗散区间优化功率输出，推导出适用于任意工作介质的最大功率效率通用公式，并研究了弱能量测量下qubit信息引擎的最优性能。

Extreme expected values and their applications in quantum information processing

We consider the probability distribution when the monotonic function $F(X)$ of the independent variable $X$ takes the maximum or minimum expected value under the two constraints of a certain probability and a certain expected value of the independent variable $X$. We proposed an equal probability and equal expected value splitting method. With this method, we proved four inequalities, and two of them can be reduced to Jensen's inequalities. Subsequently, we find that after dividing the non-monotone function $H(X)$ into multiple monotone intervals, the problem of solving the maximum and minimum…