Secure Delegated Quantum Computation (SDQC) protocols are a vital piece of the future quantum information processing global architecture since they allow end-users to perform their valuable computations on remote quantum servers without fear that a malicious quantum service provider or an eavesdropper might acquire some information about their data or algorithm. They also allow end-users to check that their computation has been performed as they have specified it. However, existing protocols all have drawbacks that limit their usage in the real world. Most require the client to either operate a single-qubit source or perform single-qubit measurements, thus requiring them to still have some quantum technological capabilities albeit restricted, or require the server to perform operations which are hard to implement on real hardware (e.g isolate single photons from laser pulses and polarisation-preserving photon-number quantum non-demolition measurements). Others remove the need for quantum communications entirely but this comes at a cost in terms of security guarantees and memory overhead on the server's side. We present an SDQC protocol which drastically reduces the technological requirements of both the client and the server while providing information-theoretic composable security. More precisely, the client only manipulates an attenuated laser pulse, while the server only handles interacting quantum emitters with a structure capable of generating spin-photon entanglement. The quantum emitter acts as both a converter from coherent laser pulses to polarisation-encoded qubits and an entanglement generator. Such devices have recently been used to demonstrate the largest entangled photonic state to date, thus hinting at the readiness of our protocol for experimental implementations.

翻译：安全委托量子计算协议是未来量子信息处理全球架构中的关键组成部分，它使得终端用户能够在远程量子服务器上执行其重要计算任务，而无需担心恶意量子服务提供商或窃听者可能获取其数据或算法的任何信息。此类协议还允许终端用户验证计算是否按其指定方式执行。然而，现有协议均存在限制其实际应用的缺陷：多数方案要求客户端具备单量子比特源操作或单量子比特测量能力，这意味着用户仍需保留一定（尽管受限的）量子技术能力；另一些方案则要求服务器执行难以在真实硬件上实现的操作（例如从激光脉冲中分离单光子、实现偏振保持的光子数量子非破坏测量等）。其他方案虽完全消除了量子通信需求，但代价是安全性保证的削弱以及服务器端内存开销的增加。本文提出一种新型安全委托量子计算协议，该协议在提供信息论可组合安全性的同时，大幅降低了客户端与服务器的技术要求。具体而言，客户端仅需操控衰减激光脉冲，而服务器仅需处理具有自旋-光子纠缠生成结构的相互作用量子发射器。该量子发射器兼具双重功能：既作为相干激光脉冲向偏振编码量子比特的转换器，又作为纠缠态生成器。此类器件近期已被用于演示迄今最大规模的纠缠光子态，这暗示了本协议已具备实验实施的可行性。