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Transfer of quantum information between physical systems of a different nature is a central matter in quantum technologies. Particularly challenging is the transfer between discrete-and continuous degrees of freedom of various harmonic oscillator systems. Here we implement a protocol for teleporting a continuous-variable optical qubit, encoded by means of coherent states, onto a discretevariable, single-rail qubit -a superposition of the vacuum-and single-photon optical states -via a hybrid entangled resource. We test our protocol on coherent states of different phases and obtain the teleported qubit with a fidelity of 0.83 ± 0.04. We also find that the phase of the resulting qubit varies consistently with that of the input, having a standard deviation of 3.8 • from the target value. Our work opens up the way to wide application of quantum information processing techniques where discrete-and continuous-variable encodings are combined within the same optical circuit.Real-world application of quantum technologies in many cases requires simultaneous use of physical systems of a different nature [1] in the hybrid fashion. For example, one of the most promising platforms for quantum information processing is superconducting circuitry, best storage times are achieved in atomic systems, whereas transmission of that information in space is better realized with photons.Within quantum optics, the hybrid paradigm consists in symbiotic involvement of states and methods from discrete (DV) and continuous (CV) variable domains. Fortes of both can thereby be employed at once; for example, the continuous part takes advantage of the de- terministic state preparation and relatively simple integration with existing information technologies [2], while the discrete side benefits from a natural photodetection basis and "built-in" entanglement distillation after losses [3]. This flexibility allows hybrid quantum technologies to offer protocols which are superior to both pure CV and DV solutions [4]. For example, using hybrid methods in quantum computing [5] and error correction [6] is favorable, compared to the mainstream CV and DV protocols, in terms of the number of resources required. Long-distance distribution of CV entanglement requires hybrid processing to mitigate the effect of propagation losses [7,8].Taking advantage of these protocols however requires a procedure for transferring quantum data between continuous and discrete qubit systems [4,9]; hybrid teleportation is therefore identified as one of the three key priorities for quantum teleportation science [10]. In this work we make a step towards this goal, demonstrating quantum teleportation by means of a hybrid entangled channel. Specifically, we develop a technique to teleport a CV qubit, encoded as a superposition of coherent states, onto a DV qubit -a superposition of the vacuum and single-photon Fock states. The protocol is conceptually different from the teleportation of photonic bits by a hybrid technique [11], in which both the input and output states are discrete-...

Two-dimensional hexagonal boron nitride (hBN) that hosts bright room-temperature single-photon emitters (SPEs) is a promising material platform for quantum information applications. An important step towards the practical application of hBN is the on-demand, position-controlled generation of SPEs. Several strategies have been reported to achieve the deterministic creation of hBN SPEs. However, they either rely on a substrate nanopatterning procedure that is not compatible with integrated photonic devices or utilize a radiation source that might cause unpredictable damage to hBN and underlying substrates. Here, we report a radiationand lithography-free route to deterministically activate hBN SPEs by nanoindentation with an atomic force microscope (AFM) tip. The method is applied to thin hBN flakes (less than 25 nm in thickness) on flat silicon-dioxide-silicon substrates that can be readily integrated into on-chip photonic devices. The achieved SPEs yields are above 30% by utilizing multiple indent sizes, and a maximum yield of 36% is demonstrated for the indent size of around 400 nm. Our results mark an important step towards the deterministic creation and integration of hBN SPEs with photonic and plasmonic on-chip devices.

Light is an irreplaceable means of communication among various quantum information processing and storage devices. Due to their different physical nature, some of these devices couple more strongly to discrete, and some to continuous degrees of freedom of a quantum optical wave. It is therefore desirable to develop a technological capability to interconvert quantum information encoded in these degrees of freedom. Here we generate and characterize an entangled state between a dual-rail (polarization-encoded) single-photon qubit and a qubit encoded as a superposition of opposite-amplitude coherent states. We furthermore demonstrate the application of this state as a resource for the interfacing of quantum information between these encodings. In particular, we show teleportation of a polarization qubit onto a freely propagating continuous-variable qubit.