Quantum teleportation is a key component in long distance quantum communication protocols. Here we demonstrate quantum teleportation of a polarization-encoded optical input state onto the joint state of a pair of nanomechanical resonators.

Quantum teleportation, the faithful transfer of an unknown input state onto a remote quantum system¹, is a key component in long-distance quantum communication protocols² and distributed quantum computing^3,4. At the same time, high-frequency nano-optomechanical systems⁵ hold great promise as nodes in a future quantum network⁶, operating on-chip at low-loss optical telecom wavelengths with long mechanical lifetimes. Recent demonstrations include entanglement between two resonators⁷, a quantum memory⁸ and microwave-to-optics transduction^9–11. Despite these successes, quantum teleportation of an optical input state onto a long-lived optomechanical memory is an outstanding challenge. Here we demonstrate quantum teleportation of a polarization-encoded optical input state onto the joint state of a pair of nanomechanical resonators. Our protocol also allows to store and retrieve an arbitrary qubit state onto a dual-rail encoded optomechanical quantum memory. This work demonstrates the full functionality of a single quantum repeater node and presents a key milestone towards applications of optomechanical systems as quantum network nodes.

The rapid development of quantum information processors has accelerated the demand for technologies that enable quantum networking. One promising approach uses mechanical resonators as an intermediary between microwave and optical fields. Signals from a superconducting, topological, or spin qubit processor can then be converted coherently to optical states at telecom wavelengths. However, current devices built from homogeneous structures suffer from added noise and a small conversion efficiency. Combining advantageous properties of different materials into a heterogeneous design should allow for superior quantum transduction devices - so far these hybrid approaches have however been hampered by complex fabrication procedures. Here we present a novel integration method, based on previous pick-and-place ideas, that can combine independently fabricated device components of different materials into a single device. The method allows for a precision alignment by continuous optical monitoring during the process. Using our method, we assemble a hybrid silicon-lithium niobate device with state-of-the-art wavelength conversion characteristics.

We present a discrete-variable quantum teleportation scheme using pulsed optomechanics. In our proposal, we demonstrate how an unknown optical input state can be transferred onto the joint state of a pair of mechanical oscillators, without physically interacting with one another. We further analyze how experimental imperfections will affect the fidelity of the teleportation and highlight how our scheme can be realized in current state-of-the-art optomechanical systems.

Nanofabricated mechanical resonators are gaining significant momentum among potential quantum technologies due to their unique design freedom and independence from naturally occurring resonances. As their functionality is widely detached from material choice, they constitute ideal tools for transducers—intermediaries between different quantum systems—and as memory elements in conjunction with quantum communication and computing devices. Their capability to host ultra-long-lived phonon modes is particularity attractive for non-classical information storage, both for future quantum technologies and for fundamental tests of physics. Here, we demonstrate a Duan–Lukin–Cirac–Zoller-type mechanical quantum memory with an energy decay time of T₁ ≈ 2 ms, which is controlled through an optical interface engineered to natively operate at telecom wavelengths. We further investigate the coherence of the memory, equivalent to the dephasing T2* for qubits, which has a power-dependent value between 15 and 112 μs. This demonstration is enabled by an optical scheme to create a superposition state of ∣0 ⟩ + ∣1 ⟩ mechanical excitations, with an arbitrary ratio between the vacuum and single-phonon components.

Silicon quantum dot spin qubits provide a promising platform for large-scale quantum computation because of their compatibility with conventional CMOS manufacturing and the long coherence times accessible using 28Si enriched material. A scalable error-corrected quantum processor, however, will require control of many qubits in parallel, while performing error detection across the constituent qubits. Spin resonance techniques are a convenient path to parallel two-axis control, while Pauli spin blockade can be used to realize local parity measurements for error detection. Despite this, silicon qubit implementations have so far focused on either single-spin resonance control, or control and measurement via voltage-pulse detuning in the two-spin singlet-triplet basis, but not both simultaneously. Here, we demonstrate an integrated device platform incorporating a silicon metal-oxide-semiconductor double quantum dot that is capable of single-spin addressing and control via electron spin resonance, combined with high-fidelity spin readout in the singlet-triplet basis.

Reliable quantum information processing in the face of errors is a major fundamental and technological challenge. Quantum error correction protects quantum states by encoding a logical quantum bit (qubit) in multiple physical qubits. To be compatible with universal fault-tolerant computations, it is essential that states remain encoded at all times and that errors are actively corrected. Here we demonstrate such active error correction on a continuously protected logical qubit using a diamond quantum processor. We encode the logical qubit in three long-lived nuclear spins, repeatedly detect phase errors by non-destructive measurements, and apply corrections by real-time feedback. The actively error-corrected qubit is robust against errors and encoded quantum superposition states are preserved beyond the natural dephasing time of the best physical qubit in the encoding. These results establish a powerful platform to investigate error correction under different types of noise and mark an important step towards fault-tolerant quantum information processing.