• Wed. Nov 29th, 2023

    Critical Thought

    Critical thoughts on quantum technologies

    Exploring the Far-Reaching Implications of Measurements in Quantum Information

    ByThemba Hadebe

    Nov 21, 2023
    Exploring the Far-Reaching Implications of Measurements in Quantum Information

    A recent paper entitled “Measurement-induced entanglement and teleportation on a noisy quantum processor” has shed new light on the fascinating field of quantum information. Published by a team of researchers from Google Quantum AI, Google Research, Stanford University, University of Texas at Austin, Cornell University, University of Massachusetts, University of Connecticut, Auburn University, University of Technology Sydney, University of California, and Columbia University, this study delves into the profound impact that measurements can have on quantum systems.

    In the realm of quantum theory, measurements play a crucial role by collapsing the wavefunction of a system. This collapse gives rise to phenomena such as teleportation, effectively altering the “arrow of time” that governs unitary evolution. Furthermore, when measurements are incorporated into many-body dynamics, they can give rise to emergent patterns of quantum information in spacetime. These patterns go beyond the established paradigms for characterizing phases, both in and out of equilibrium.

    For present-day noisy intermediate-scale quantum (NISQ) processors, however, the experimental realization of measurement-induced phenomena can be challenging. This is due to hardware limitations and the inherent stochastic nature of quantum measurement. Nevertheless, the research team tackled these experimental hurdles head-on and successfully explored measurement-induced quantum information phases using up to 70 superconducting qubits.

    The researchers employed a clever approach to overcome the limitations of NISQ processors. By exploiting the interchangeability of space and time, they used a duality mapping technique to bypass mid-circuit measurements. This allowed them to access various manifestations of the underlying phases, ranging from entanglement scaling to measurement-induced teleportation. Notably, in their study, they observed finite-sized signatures of a phase transition and developed a decoding protocol that correlated experimental measurements with classical simulation data.

    One intriguing aspect of this research is the distinct sensitivity of different phases to noise. The phases exhibited remarkably different responses to noise, and this disparity was leveraged by the researchers to transform an inherent hardware limitation into a valuable diagnostic tool. This innovative approach showcases the potential to extract useful information from quantum systems, even in the presence of noise.

    Overall, this work opens up exciting possibilities for realizing measurement-induced physics at scales that push the boundaries of current NISQ processors. By elucidating the far-reaching implications of measurements on quantum systems, the researchers are advancing our understanding of fundamental quantum phenomena and paving the way for future breakthroughs in quantum information science.

    Frequently Asked Questions

    Q: What is a superconducting qubit?

    A: A superconducting qubit is the basic unit of quantum information in a superconducting quantum computer. It is typically implemented using superconducting circuits that exploit the unique properties of superconductors to encode and manipulate quantum states.

    Q: What are quantum information phases?

    A: Quantum information phases refer to patterns or states of quantum information that emerge in a system when measurements are integrated into its dynamics. These phases go beyond traditional paradigms for characterizing quantum systems and can exhibit unique properties and phenomena.

    Q: What is a noisy intermediate-scale quantum (NISQ) processor?

    A: A noisy intermediate-scale quantum processor is a type of quantum computer that operates with a moderate number of qubits (typically tens to hundreds) but is subject to noise and imperfections due to hardware limitations. NISQ processors are currently at the forefront of quantum computing research and development.

    Q: What is entanglement scaling?

    A: Entanglement scaling refers to the study of how the degree of entanglement between qubits scales with the size of a quantum system. Entanglement is a fundamental aspect of quantum mechanics and plays a key role in various quantum information processing tasks.


    “Measurement-induced entanglement and teleportation on a noisy quantum processor” – Google Quantum AI and Collaborators. Nature, 622(8329), 481-486. https://doi.org/10.1038/s41586-023-06505-7