38 research outputs found
Controlling quantum many-body dynamics in driven Rydberg atom arrays
The control of nonequilibrium quantum dynamics in many-body systems is challenging because interactions typically lead to thermalization and a chaotic spreading throughout Hilbert space. We investigate nonequilibrium dynamics after rapid quenches in a many-body system composed of 3 to 200 strongly interacting qubits in one and two spatial dimensions. Using a programmable quantum simulator based on Rydberg atom arrays, we show that coherent revivals associated with so-called quantum many-body scars can be stabilized by periodic driving, which generates a robust subharmonic response akin to discrete time-crystalline order. We map Hilbert space dynamics, geometry dependence, phase diagrams, and system-size dependence of this emergent phenomenon, demonstrating new ways to steer complex dynamics in many-body systems and enabling potential applications in quantum information science
High-fidelity parallel entangling gates on a neutral atom quantum computer
The ability to perform entangling quantum operations with low error rates in
a scalable fashion is a central element of useful quantum information
processing. Neutral atom arrays have recently emerged as a promising quantum
computing platform, featuring coherent control over hundreds of qubits and
any-to-any gate connectivity in a flexible, dynamically reconfigurable
architecture. The major outstanding challenge has been to reduce errors in
entangling operations mediated through Rydberg interactions. Here we report the
realization of two-qubit entangling gates with 99.5% fidelity on up to 60 atoms
in parallel, surpassing the surface code threshold for error correction. Our
method employs fast single-pulse gates based on optimal control, atomic dark
states to reduce scattering, and improvements to Rydberg excitation and atom
cooling. We benchmark fidelity using several methods based on repeated gate
applications, characterize the physical error sources, and outline future
improvements. Finally, we generalize our method to design entangling gates
involving a higher number of qubits, which we demonstrate by realizing
low-error three-qubit gates. By enabling high-fidelity operation in a scalable,
highly connected system, these advances lay the groundwork for large-scale
implementation of quantum algorithms, error-corrected circuits, and digital
simulations.Comment: 5 pages, 4 figures. Methods: 13 pages, 10 figure
Logical quantum processor based on reconfigurable atom arrays
Suppressing errors is the central challenge for useful quantum computing,
requiring quantum error correction for large-scale processing. However, the
overhead in the realization of error-corrected ``logical'' qubits, where
information is encoded across many physical qubits for redundancy, poses
significant challenges to large-scale logical quantum computing. Here we report
the realization of a programmable quantum processor based on encoded logical
qubits operating with up to 280 physical qubits. Utilizing logical-level
control and a zoned architecture in reconfigurable neutral atom arrays, our
system combines high two-qubit gate fidelities, arbitrary connectivity, as well
as fully programmable single-qubit rotations and mid-circuit readout. Operating
this logical processor with various types of encodings, we demonstrate
improvement of a two-qubit logic gate by scaling surface code distance from d=3
to d=7, preparation of color code qubits with break-even fidelities,
fault-tolerant creation of logical GHZ states and feedforward entanglement
teleportation, as well as operation of 40 color code qubits. Finally, using
three-dimensional [[8,3,2]] code blocks, we realize computationally complex
sampling circuits with up to 48 logical qubits entangled with hypercube
connectivity with 228 logical two-qubit gates and 48 logical CCZ gates. We find
that this logical encoding substantially improves algorithmic performance with
error detection, outperforming physical qubit fidelities at both cross-entropy
benchmarking and quantum simulations of fast scrambling. These results herald
the advent of early error-corrected quantum computation and chart a path toward
large-scale logical processors.Comment: See ancillary files: five supplementary movies and captions. Main
text + Method
Early Pleistocene faunivorous hominins were not kleptoparasitic, and this impacted the evolution of human anatomy and socio-ecology
Humans are unique in their diet, physiology and socio-reproductive behavior compared to other primates. They are also unique in the ubiquitous adaptation to all biomes and habitats. From an evolutionary perspective, these trends seem to have started about two million years ago, coinciding with the emergence of encephalization, the reduction of the dental apparatus, the adoption of a fully terrestrial lifestyle, resulting in the emergence of the modern anatomical bauplan, the focalization of certain activities in the landscape, the use of stone tools, and the exit from Africa. It is in this period that clear taphonomic evidence of a switch in diet with respect to Pliocene hominins occurred, with the adoption of carnivory. Until now, the degree of carnivorism in early humans remained controversial. A persistent hypothesis is that hominins acquired meat irregularly (potentially as fallback food) and opportunistically through klepto-foraging. Here, we test this hypothesis and show, in contrast, that the butchery practices of early Pleistocene hominins (unveiled through systematic study of the patterning and intensity of cut marks on their prey) could not have resulted from having frequent secondary access to carcasses. We provide evidence of hominin primary access to animal resources and emphasize the role that meat played in their diets, their ecology and their anatomical evolution, ultimately resulting in the ecologically unrestricted terrestrial adaptation of our species. This has major implications to the evolution of human physiology and potentially for the evolution of the human brain
Controlling quantum many-body dynamics in driven Rydberg atom arrays
Dynamic stabilization of an array
Large-scale systems comprising one-dimensional chains and two-dimensional arrays of excited atoms held in a programmable optical lattice are a powerful platform with which to simulate emergent phenomena. Bluvstein
et al.
built an array of up to 200 Rydberg atoms and subjected the system to periodic excitation. Under such driven excitation, they found that the array of atoms stabilized, freezing periodically into what looked like time crystals. Understanding and controlling the dynamic interactions in quantum many-body systems lies at the heart of contemporary condensed matter physics and the exotic phenomena that can occur.
Science
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