Tower of Structured Excited States from Measurements

• URL: http://arxiv.org/abs/2411.17020v1
• Date: Tue, 26 Nov 2024 01:07:46 GMT
• Title: Tower of Structured Excited States from Measurements
• Authors: Yuxuan Guo, Yuto Ashida,
• Abstract summary: We introduce a log-depth protocol leveraging quantum phase estimation to measure a global observable. We demonstrate its capability to prepare towers of structured excited states that are useful in quantum metrology. Our results expand the utility of measurement-based approaches to accessing highly entangled states in quantum many-body systems.
• Score: 0.07673339435080445
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• Abstract: Preparing highly entangled quantum states is a key challenge in quantum metrology and quantum information science. Measurements, especially those of global observables, offer a simple and efficient way to generate entanglement between subsystems when they are measured as a whole. We introduce a log-depth protocol leveraging quantum phase estimation to measure a global observable, such as total magnetization and momentum. We demonstrate its capability to prepare towers of structured excited states that are useful in quantum metrology; examples include quantum many-body scars in various models, including the Affleck-Kennedy-Lieb-Tasaki (AKLT) model, the constrained domain-wall model, and the spin-$\frac{1}{2}$ and spin-$1$ XX chains. The same method is also applicable to preparing the Dicke states of high weight. In addition, we propose a protocol for momentum measurement that avoids disturbing the system, facilitating the preparation of states beyond the above construction, such as the Arovas $A$ state of the AKLT Hamiltonian. Our results expand the utility of measurement-based approaches to accessing highly entangled states in quantum many-body systems.

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