66 research outputs found
Nearly Deterministic Bell Measurement for Multiphoton Qubits and Its Application to Quantum Information Processing
We propose a Bell measurement scheme by employing a logical qubit in
Greenberger-Horne-Zeilinger (GHZ) entanglement with an arbitrary number of
photons. Remarkably, the success probability of the Bell measurement as well as
teleportation of the GHZ entanglement can be made arbitrarily high using only
linear optics elements and photon on-off measurements as the number of photons
increases. Our scheme outperforms previous proposals using single photon qubits
when comparing the success probabilities in terms of the average photon usages.
It has another important advantage for experimental feasibility that it does
not require photon number resolving measurements. Our proposal provides an
alternative candidate for all-optical quantum information processing.Comment: 7 pages (including supplementary material), 2 figures, to be
published in Phys. Rev. Let
InstructRL: Instruction-Following Agents with Jointly Pre-Trained Vision-Language Models
Humans are excellent at understanding language and vision to accomplish a
wide range of tasks. In contrast, creating general instruction-following
embodied agents remains a difficult challenge. Prior work that uses pure
language-only models lack visual grounding, making it difficult to connect
language instructions with visual observations. On the other hand, methods that
use pre-trained vision-language models typically come with divided language and
visual representations, requiring designing specialized network architecture to
fuse them together. We propose a simple yet effective model for robots to solve
instruction-following tasks in vision-based environments. Our \ours method
consists of a multimodal transformer that encodes visual observations and
language instructions, and a policy transformer that predicts actions based on
encoded representations. The multimodal transformer is pre-trained on millions
of image-text pairs and natural language text, thereby producing generic
cross-modal representations of observations and instructions. The policy
transformer keeps track of the full history of observations and actions, and
predicts actions autoregressively. We show that this unified transformer model
outperforms all state-of-the-art pre-trained or trained-from-scratch methods in
both single-task and multi-task settings. Our model also shows better model
scalability and generalization ability than prior work
Controllability-Aware Unsupervised Skill Discovery
One of the key capabilities of intelligent agents is the ability to discover
useful skills without external supervision. However, the current unsupervised
skill discovery methods are often limited to acquiring simple, easy-to-learn
skills due to the lack of incentives to discover more complex, challenging
behaviors. We introduce a novel unsupervised skill discovery method,
Controllability-aware Skill Discovery (CSD), which actively seeks complex,
hard-to-control skills without supervision. The key component of CSD is a
controllability-aware distance function, which assigns larger values to state
transitions that are harder to achieve with the current skills. Combined with
distance-maximizing skill discovery, CSD progressively learns more challenging
skills over the course of training as our jointly trained distance function
reduces rewards for easy-to-achieve skills. Our experimental results in six
robotic manipulation and locomotion environments demonstrate that CSD can
discover diverse complex skills including object manipulation and locomotion
skills with no supervision, significantly outperforming prior unsupervised
skill discovery methods. Videos and code are available at
https://seohong.me/projects/csd/Comment: ICML 202
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