Process estimation in presence of time-invariant memory effects
arXiv:1409.4268 · doi:10.1103/PhysRevA.92.042315
Abstract
Any repeated use of a fixed experimental instrument is subject to memory effects. We design an estimation method uncovering the details of the underlying interaction between the system and the internal memory without having any experimental access to memory degrees of freedom. In such case, by definition, any memoryless quantum process tomography (QPT) fails, because the observed data sequences do not satisfy the elementary condition of statistical independence. However, we show that the randomness implemented in certain QPT schemes is sufficient to guarantee the emergence of observable "statistical" patterns containing complete information on the memory channels. We demonstrate the algorithm in details for case of qubit memory channels with two-dimensional memory. Interestingly, we found that for arbitrary estimation method the memory channels generated by controlled unitary interactions are indistinguishable from memoryless unitary channels.
5 pages, 2 figures
References in corpus (7)
- Experimental Quantum State Tomography of Optical Fields and Ultrafast Statistical Sampling
- Efficient quantum state tomography
- Indirect Quantum Tomography of Quadratic Hamiltonians
- Precision-guaranteed quantum tomography
- Robust error bars for quantum tomography
- Sanov and Central Limit Theorems for output statistics of quantum Markov chains
- Identifiability of Open Quantum Systems