Counterfactual universal quantum computation

Loss tolerance in one-way quantum computation via counterfactual error correction

We introduce a scheme for fault tolerantly dealing with losses (or other "leakage" errors) in cluster state computation that can tolerate up to 50% qubit loss. This is achieved passively using an adaptive strategy of measurement - no coherent measurements or coherent correction is required. Since the scheme relies on inferring information about what would have been the outcome of a measurement had one been able to carry it out, we call this "counterfactual" error correction.

Interaction-free measurements and counterfactual computation in IBM quantum computers

The possibility of interaction-free measurements and counterfactual computations is a striking feature of quantum mechanics pointed out around 20 years ago. We implement such phenomena in actual 5-qubit, 15-qubit and 20-qubit IBM quantum computers by means of simple quantum circuits. The results are in general close to the theoretical expectations. For the larger circuits (with numerous gates and consequently larger errors) we implement a simple error mitigation procedure which improve appreciably the performance.

Counterfactual Concealed Telecomputation

Distributed computing is a fastest growing field -- enabling virtual computing, parallel computing, and distributed storage. By exploiting the counterfactual techniques, we devise a distributed blind quantum computation protocol to perform a universal two-qubit controlled unitary operation for any input state without using preshared entanglement and without exchanging physical particles between remote parties. This distributed protocol allows Bob to counterfactully apply an arbitrary unitary operator to Alice's qubit in probabilistic fashion, without revealing the operator to her, using a cont…

A counterfactual Rydberg gate for photons

Quantum computation with photons requires efficient two photon gates. We put forward a two photon entangling gate which uses an intermediate atomic system. The system includes a single Rydberg atom which can switch on and off photon absorption in an ensemble using the dipole blockade. The gate is based in a counterfactual protocol. The mere possibility of an absorption that can only occur with a vanishing probability steers the photons to the desired final state.

反事实局域友好性：一个ε有界的无相互作用佯谬与一个抗扰动的三箱不等式

Counterfactual Local Friendliness: An epsilon-Bounded Interaction-Free Paradox and a Disturbance-Robust Three-Box Inequality

本研究提出ε有界无相互作用的反事实局域友好性佯谬，推导抗扰动三箱非互文性界并证明量子理论可违反该界，揭示反事实佯谬的核心是单世界叙事中主体事实的不相容性。

Exploiting Particle Statistics in Quantum Computation

We describe a plausible-speculative form of quantum computation which exploits particle (fermionic, bosonic) statistics, under a generalized, counterfactual interpretation thereof. In the idealized situation of an isolated system, it seems that this form of computation yields to NP-complete=P.

无粒子交换的确定性隐形传态与通用计算

Deterministic Teleportation and Universal Computation Without Particle Exchange

本文提出控制端与目标端间无粒子交换的通用受控相位门，借此实现确定性隐形传态、远程克隆及全套无交换量子计算，并验证其在现实比特误差下的实验可行性。

Quantum computation based on particle statistics

In spite of their evident logical character, particle statistics symmetries are not among the inherently quantum features exploited in quantum computation. A difficulty may be that, being a constant of motion of a unitary evolution, a particle statistics symmetry cannot affect the course of such an evolution. We try to avoid this possible deadlock by introducing a generalized (counterfactual, blunt) formulation where this type of symmetry becomes a watchdog effect shaping the evolution of a unitary computation process. The work is an exploration.