- When can one experiment replace another?by Frits VerhagenImagine two instruments designed to distinguish between several competing explanations of a physical system. Both produce noisy observations. Which instrument gives us more information? One way to compare them is to pick a particular task and see which performs better. But there is a more ambitious possibility: perhaps the observations … Continue reading →
- The tale of two proofs of the strong converseby Marco TomamichelThe strong converse problem What happens if we try to communicate quantum information through a noisy quantum channel at a rate above its capacity? At first sight, the answer seems obvious: it should not work. After all, this is what we mean by the quantum capacity . Below capacity, there … Continue reading →
- Testing Conditional Mutual Information in Discrete Distributionsby Jan SeyfriedConditional independence describes the situation where correlations between two variables A and C can be explained entirely through the value of a third variable B. We then say that A and C are conditionally independent given B. In our work, we study how efficiently this property can be tested when … Continue reading →
- New additivity properties in quantum resource theoriesby Roberto RubboliOptimization problems involving quantum relative entropies are ubiquitous in quantum information theory. Some prominent examples include the optimization of the fidelity function or the Umegaki relative entropy over a set of states satisfying some specific constraints. In our work, we address this general problem and show that our methods are … Continue reading →
- Fundamental limits on quantum cloning from the no-signalling principleby Yanglin HuThe no-cloning theorem states that within the framework of quantum mechanics, there does not exist any universal procedure that can replicate an unknown quantum state reliably. This fundamental principle was initially formalized in 1982 and later extended in various directions. The no-cloning theorem has rich implications in quantum cryptography, ensuring … Continue reading →
- Privacy and correctness trade-offs for information-theoretically secure quantum homomorphic encryptionby Yanglin HuHomomorphic encryption, which allows a server to compute on encrypted data of a client without first decrypting it, is like a “Swiss army knife” of classical cryptography. Namely, by treating homomorphic encryption as a cryptographic primitive, a broad range of cryptographic notions such as multiparty secure computation and private information … Continue reading →
- Fundamental Limits on Correlated Catalytic State Transformationsby Roberto RubboliQuantum state transformation is a fundamental problem in quantum resource theories. Resource theories offer a general framework to quantify the usefulness of quantum states and their inconvertibility under free operations. A resource theory is defined by a subset of quantum states called free states and a set of free operations … Continue reading →
- Bandits roaming Hilbert Spaceby Josep LumbrerasThe (classical) multi-armed bandit problem The multi-armed bandit problem is a simple model of decision-making with uncertainty that lies in the class of classical reinforcement learning problems. Given a set of arms, a learner interacts sequentially with these arms sampling a reward at each round and the objective of the … Continue reading →
- Quantum advantage with noisy shallow circuitsby Marco TomamichelAs larger and larger prototypes of quantum computers are being developed, one of the most exciting challenges in the theory of quantum computing is to find computational problems that can be solved by an noisy intermediate-scale noisy quantum devices, but are beyond the capabilities of existing classical computers. In joint … Continue reading →
QIT@CQT – Quantum Information Theory at the Centre for Quantum Technologies in Singapore
