Abstract
In an ideal quantum measurement, the wave function of a quantum system collapses to an eigenstate of the measured observable, and the corresponding eigenvalue determines the measurement outcome. If the observable commutes with the system Hamiltonian, repeated measurements yield the same result and thus minimally disturb the system. Seminal quantum optics experiments have achieved such quantum non-demolition (QND) measurements of systems with few degrees of freedom. In contrast, here we describe how the QND measurement of a complex many-body observable, the Hamiltonian of an interacting many-body system, can be implemented in a trapped-ion analog quantum simulator. Through a single-shot measurement, the many-body system is prepared in a narrow band of (highly excited) energy eigenstates, and potentially even a single eigenstate. Our QND scheme, which can be carried over to other platforms of quantum simulation, provides a framework to investigate experimentally fundamental aspects of equilibrium and non-equilibrium statistical physics including the eigenstate thermalization hypothesis and quantum fluctuation relations.
Highlights
In an ideal quantum measurement, the wave function of a quantum system collapses to an eigenstate of the measured observable, and the corresponding eigenvalue determines the measurement outcome
We note that quantum optics provides with several examples of quantum non-demolition (QND) measurements; these have so far been confined to observables representing few quantum degrees of freedom[14,15,16,17,18,19,20]
The ability to prepare and measure energy eigenstates provides us with a unique tool to address experimentally fundamental problems in quantum statistical physics, such as the eigenstate thermalization hypothesis (ETH)[22,23,24], which asserts that single energy eigenstates of an ergodic system encode thermodynamic equilibrium properties
Summary
In an ideal quantum measurement, the wave function of a quantum system collapses to an eigenstate of the measured observable, and the corresponding eigenvalue determines the measurement outcome. 1234567890():,; Recent experimental advances provide intriguing opportunities in the preparation, manipulation, and measurement of the quantum state of engineered complex many-body systems This includes the ability to address individual sites of lattice systems enabling single-shot read-out of single-particle observables, as demonstrated by the quantum gas microscope for atoms in optical lattices[1,2], single-spin or qubit read-out of trapped ions[3,4,5,6,7] and Rydberg tweezers arrays[8,9,10,11,12], and superconducting qubits[13,14]. Developing the capability to turn QND measurements on and off allows one to alternate between time periods of free evolution of the unobserved many-body quantum system and energy measurement This allows quantum feedback in a many-body system conditional to measurement outcomes, and in particular provides a framework to monitor non-equilibrium dynamics and processes in quantum thermodynamics[25], including measurement of work functions and quantum fluctuation relations (QFRs)[26,27,28]. Our implementation in an analog quantum device should be contrasted to QND measurement of H^ via a phase estimation algorithm[29], which requires a universal (digital) quantum computer
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
