An integrated space-to-ground quantum communication network over 4,600 kilometres.

Quantum key distribution (QKD)1,2 has the potential to enable secure communication and information transfer3. In the laboratory, the feasibility of point-to-point QKD is evident from the early proof-of-concept demonstration in the laboratory over 32 centimetres4; this distance was later extended to the 100-kilometre scale5,6 with decoy-state QKD and more recently to the 500-kilometre scale7-10 with measurement-device-independent QKD. Several small-scale QKD networks have also been tested outside the laboratory11-14. However, a global QKD network requires a practically (not just theoretically) secure and reliable QKD network that can be used by a large number of users distributed over a wide area15. Quantum repeaters16,17 could in principle provide a viable option for such a global network, but they cannot be deployed using current technology18. Here we demonstrate an integrated space-to-ground quantum communication network that combines a large-scale fibre network of more than 700 fibre QKD links and two high-speed satellite-to-ground free-space QKD links. Using a trusted relay structure, the fibre network on the ground covers more than 2,000 kilometres, provides practical security against the imperfections of realistic devices, and maintains long-term reliability and stability. The satellite-to-ground QKD achieves an average secret-key rate of 47.8 kilobits per second for a typical satellite pass-more than 40 times higher than achieved previously. Moreover, its channel loss is comparable to that between a geostationary satellite and the ground, making the construction of more versatile and ultralong quantum links via geosynchronous satellites feasible. Finally, by integrating the fibre and free-space QKD links, the QKD network is extended to a remote node more than 2,600 kilometres away, enabling any user in the network to communicate with any other, up to a total distance of 4,600 kilometres.

Entanglement-based secure quantum cryptography over 1,120 kilometres.

Quantum key distribution (QKD)1-3 is a theoretically secure way of sharing secret keys between remote users. It has been demonstrated in a laboratory over a coiled optical fibre up to 404 kilometres long4-7. In the field, point-to-point QKD has been achieved from a satellite to a ground station up to 1,200 kilometres away8-10. However, real-world QKD-based cryptography targets physically separated users on the Earth, for which the maximum distance has been about 100 kilometres11,12. The use of trusted relays can extend these distances from across a typical metropolitan area13-16 to intercity17 and even intercontinental distances18. However, relays pose security risks, which can be avoided by using entanglement-based QKD, which has inherent source-independent security19,20. Long-distance entanglement distribution can be realized using quantum repeaters21, but the related technology is still immature for practical implementations22. The obvious alternative for extending the range of quantum communication without compromising its security is satellite-based QKD, but so far satellite-based entanglement distribution has not been efficient23 enough to support QKD. Here we demonstrate entanglement-based QKD between two ground stations separated by 1,120 kilometres at a finite secret-key rate of 0.12 bits per second, without the need for trusted relays. Entangled photon pairs were distributed via two bidirectional downlinks from the Micius satellite to two ground observatories in Delingha and Nanshan in China. The development of a high-efficiency telescope and follow-up optics crucially improved the link efficiency. The generated keys are secure for realistic devices, because our ground receivers were carefully designed to guarantee fair sampling and immunity to all known side channels24,25. Our method not only increases the secure distance on the ground tenfold but also increases the practical security of QKD to an unprecedented level.

In-orbit dark count rate performance and radiation damage high-temperature annealing of silicon avalanche photodiode single-photon detectors of the Micius satellite.

Silicon avalanche photodiode (APD) single-photon detectors in space are continuously affected by radiation, which gradually degrades their dark count performance. From August 2016 to June 2023, we conducted approximately seven years (2507 days) of in-orbit monitoring of the dark count performance of APD single-photon detectors on the Micius Quantum Science Experimental Satellite. The results showed that due to radiation effects, the dark count growth rate was approximately 6.79 cps/day @ -24 °C and 0.37 cps/day @ -55 °C, with a significant suppression effect on radiation-induced dark counts at lower operating temperature. Based on the proposed radiation damage induced dark count annealing model, simulations were conducted for the in-orbit dark counts of the detector, the simulation results are consistent with in-orbit test data. In May 2022, four of these detectors underwent a cumulative 5.7 hours high-temperature annealing test at 76 °C, dark count rate shows no measurable changes, consistent with annealing model. As of now, these ten APD single-photon detectors on the Micius Quantum Science Experimental Satellite have been in operation for approximately 2507 days and are still functioning properly, providing valuable experience for the future long-term space applications of silicon APD single-photon detectors.

Oncolytic virotherapy evolved into the fourth generation as tumor immunotherapy.

BACKGROUND: Oncolytic virotherapy (OVT) is a promising anti-tumor modality that utilizes oncolytic viruses (OVs) to preferentially attack cancers rather than normal tissues. With the understanding particularly in the characteristics of viruses and tumor cells, numerous innovative OVs have been engineered to conquer cancers, such as Talimogene Laherparepvec (T-VEC) and tasadenoturev (DNX-2401). However, the therapeutic safety and efficacy must be further optimized and balanced to ensure the superior safe and efficient OVT in clinics, and reasonable combination therapy strategies are also important challenges worthy to be explored. MAIN BODY: Here we provided a critical review of the development history and status of OVT, emphasizing the mechanisms of enhancing both safety and efficacy. We propose that oncolytic virotherapy has evolved into the fourth generation as tumor immunotherapy. Particularly, to arouse T cells by designing OVs expressing bi-specific T cell activator (BiTA) is a promising strategy of killing two birds with one stone. Amazing combination of therapeutic strategies of OVs and immune cells confers immense potential for managing cancers. Moreover, the attractive preclinical OVT addressed recently, and the OVT in clinical trials were systematically reviewed. CONCLUSION: OVs, which are advancing into clinical trials, are being envisioned as the frontier clinical anti-tumor agents coming soon.

Satellite-to-ground quantum key distribution.

Quantum key distribution (QKD) uses individual light quanta in quantum superposition states to guarantee unconditional communication security between distant parties. However, the distance over which QKD is achievable has been limited to a few hundred kilometres, owing to the channel loss that occurs when using optical fibres or terrestrial free space that exponentially reduces the photon transmission rate. Satellite-based QKD has the potential to help to establish a global-scale quantum network, owing to the negligible photon loss and decoherence experienced in empty space. Here we report the development and launch of a low-Earth-orbit satellite for implementing decoy-state QKD-a form of QKD that uses weak coherent pulses at high channel loss and is secure because photon-number-splitting eavesdropping can be detected. We achieve a kilohertz key rate from the satellite to the ground over a distance of up to 1,200 kilometres. This key rate is around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. The establishment of a reliable and efficient space-to-ground link for quantum-state transmission paves the way to global-scale quantum networks.

Ground-to-satellite quantum teleportation.

An arbitrary unknown quantum state cannot be measured precisely or replicated perfectly. However, quantum teleportation enables unknown quantum states to be transferred reliably from one object to another over long distances, without physical travelling of the object itself. Long-distance teleportation is a fundamental element of protocols such as large-scale quantum networks and distributed quantum computation. But the distances over which transmission was achieved in previous teleportation experiments, which used optical fibres and terrestrial free-space channels, were limited to about 100 kilometres, owing to the photon loss of these channels. To realize a global-scale 'quantum internet' the range of quantum teleportation needs to be greatly extended. A promising way of doing so involves using satellite platforms and space-based links, which can connect two remote points on Earth with greatly reduced channel loss because most of the propagation path of the photons is in empty space. Here we report quantum teleportation of independent single-photon qubits from a ground observatory to a low-Earth-orbit satellite, through an uplink channel, over distances of up to 1,400 kilometres. To optimize the efficiency of the link and to counter the atmospheric turbulence in the uplink, we use a compact ultra-bright source of entangled photons, a narrow beam divergence and high-bandwidth and high-accuracy acquiring, pointing and tracking. We demonstrate successful quantum teleportation of six input states in mutually unbiased bases with an average fidelity of 0.80 ± 0.01, well above the optimal state-estimation fidelity on a single copy of a qubit (the classical limit). Our demonstration of a ground-to-satellite uplink for reliable and ultra-long-distance quantum teleportation is an essential step towards a global-scale quantum internet.

Quantum State Transfer over 1200 km Assisted by Prior Distributed Entanglement.

Long-distance quantum state transfer (QST), which can be achieved with the help of quantum teleportation, is a core element of important quantum protocols. A typical situation for QST based on teleportation is one in which two remote communication partners (Alice and Bob) are far from the entanglement source (Charlie). Because of the atmospheric turbulence, it is challenging to implement the Bell-state measurement after photons propagate in atmospheric channels. In previous long-distance free-space experiments, Alice and Charlie always perform local Bell-state measurement before the entanglement distribution process is completed. Here, by developing a highly stable interferometer to project the photon into a hybrid path-polarization dimension and utilizing the satellite-borne entangled photon source, we demonstrate proof-of-principle QST at the distance of over 1200 km assisted by prior quantum entanglement shared between two distant ground stations with the satellite Micius. The average fidelity of transferred six distinct quantum states is 0.82±0.01, exceeding the classical limit of 2/3 on a single copy of a qubit.

Synchronization using quantum photons for satellite-to-ground quantum key distribution.

Time synchronization is crucial for quantum key distribution (QKD) systems. In order to compensate for the time drift caused by the Doppler effect and adapt to the unstable optical link in satellite-to-ground QKD, previous demonstrations generally adopted synchronization methods requiring additional hardware. In this paper, we present a novel synchronization method based on the detected quantum photons, thus simplifying additional hardware and reducing the complexity and cost. This method adopts target frequency scanning to realize fast frequency recovery, utilizes polynomial fitting to compensate for the Doppler effect, and takes use of the vacuum state in the decoy-state BB84 protocol to recover the time offset. This method can avoid the influence of synchronization light jitter, thus improving the synchronization precision and the secure keys as well. Successful satellite-to-ground QKD based on this new synchronization scheme has been conducted to demonstrate its feasibility and performance. The presented scheme provides an effective synchronization solution for quantum communication applications.

The old CEACAMs find their new role in tumor immunotherapy.

Carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) contain 12 family members(CEACAM1、CEACAM3、CEACAM4、CEACAM5、CEACAM6、CEACAM7、CEACAM8、CEACAM16、CEACAM18、CEACAM19、CEACAM20 and CEACAM21)and are expressed diversely in different normal and tumor tissues. CEA (CEACAM5) has been used as a tumor biomarker since 1965. Here we review the latest research and development of the structures, expression, and function of CEACAMs in normal and tumor tissues, and their application in the tumor diagnosis, prognosis, and treatment. We focus on recent clinical studies of CEA targeted cancer immunotherapies, including bispecific antibody (BsAb) for radio-immuno-therapy and imaging, bispecific T cell engager (BiTE) and chimeric antigen receptor T cells (CAR-T). We summarize the promising clinical relevance and challenges of these approaches and give perspective view for future research. This review has important implications in understanding the diversified biology of CEACAMs in normal and tumor tissues, and their new role in tumor immunotherapy.

Correction to: The old CEACAMs find their new role in tumor immunotherapy.

Correction is needed to the original version of this article.

Reduced Consolation Behaviors in Physically Stressed Mandarin Voles: Involvement of Oxytocin, Dopamine D2, and Serotonin 1A Receptors Within the Anterior Cingulate Cortex.

BACKGROUND: Consolation is a type of empathy-like behavior that has recently been observed in some socially living rodents. Despite the growing body of literature suggesting that stress affects empathy, the relationship between stress and consolation remains understudied at the preclinical level. Here, we examined the effects of chronic emotional stress or physical stress exposure on consolation and emotional behaviors by using the socially monogamous mandarin vole (Microtus mandarinus) in both males and females. METHOD/RESULTS: Physical stress voles were exposed to 14-day social defeat stress, whereas emotional stress voles vicariously experienced the defeat of their partners. We found that physical stress, but not emotional stress, voles showed reduced grooming toward their defeated partners and increased anxiety- and despair-like behaviors. Meanwhile, physical stress voles exhibited decreased neural activity in the anterior cingulate cortex, which is centrally involved in empathy. The densities of oxytocin receptors, dopamine D2 receptors, and serotonin 1A-receptors within the anterior cingulate cortex were significantly decreased in the physical stress group compared with controls. All the behavioral and physiological changes were similar between the sexes. Finally, we found that the reduced consolation behavior and some anxiety-like syndromes in physical stress voles could be alleviated by pretreatment with an oxytocin receptor, D2 receptors, or serotonin 1A-receptor agonist within the anterior cingulate cortex, whereas injections of corresponding receptor antagonists to the control voles decreased the consolation behavior and increased some anxiety-like behaviors. CONCLUSIONS: Our results indicated that chronic physical stress exposure impaired consolation and induced anxiety-like behaviors in mandarin voles and oxytocin receptors, 5-HT1A receptors, and D2 receptors within the anterior cingulate cortex may play important roles in these processes.

Novel transcription regulatory sequences and factors of the immune evasion protein ICP47 (US12) of herpes simplex viruses.

BACKGROUND: Herpes simplex virus (HSV) can cause encephalitis. Its infected cell polypeptide 47 (ICP47), encoded by immediate-early gene US12, promotes immune escape. ICP47 was modified in the clinically approved oncolytic HSV (oHSV) T-Vec. However, transcription regulatory sequence (TRS) and transcription regulatory factor (TRF) of HSV US12 are seldom reported. METHODS: Previously, our laboratory isolated a new HSV strain named HSV-1-LXMW from a male patient with oral herpes in Beijing, China. Firstly, the genetic tree was used to analyze its genetic relationship. The US12 TRS and TRF in HSV-1-LXMW were found by using predictive software. Secondly, the further verification by the multi-sequence comparative analysis shown that the upstream DNA sequence of HSV US12 gene contained the conserved region. Finally, the results of literature search shown that the expression of transcription factors was related to the tissue affinity of HSV-1 and HSV-2, so as to increase the new understanding of the transcriptional regulation of HSV biology and oncolytic virus (OVs) therapy. RESULTS: Here we reported the transcriptional regulation region sequence of our new HSV-1-LXMW, and its close relationship with HSV-1-CR38 and HSV-1-17. Importantly we identified eight different kinds of novel TRSs and TRFs of HSV US12 for the first time, and found they are conserved among HSV-1 (c-Rel, Elk-1, Pax-4), HSV-2 (Oct-1, CF2-II, E74A, StuAp) or both HSVs (HNF-4). The TRFs c-Rel and Oct-1 are biologically functional respectively in immune escape and viral replication during HSV infection. CONCLUSIONS: Our findings have important implication to HSV biology, infection, immunity and oHSVs.

Optically injected intensity-stable pulse source for secure quantum key distribution.

The security of decoy-state quantum key distribution (QKD) highly depends on the accurate control of multiple intensity states. Although several theoretical studies on the QKD with loosely controlled source intensities have been proposed, there is still a large gap between the experimental realization and the theoretical analysis. In this paper, we adopt the gain-switching method to generate short optical pulses, and the corresponding intensity stabilities are quantitatively measured. The method via optical injection is proposed to make effective reductions of the intensity fluctuations from 6.47%∼1.59% to 1.95%∼1.15% at different optical powers. QKD performance adopting the experimental results is also analyzed and discussed. For a typical 40 dB high-attenuation QKD system, the relative increase on the secure key rates reaches 51.89% for the corresponding intensity fluctuations of 1.15% with optical injection and 1.59% without optical injection. The presented intensity-stable optical pulse source can find wide applications in different QKD protocols, such as BB84, DPS, COW, etc.

High-speed robust polarization modulation for quantum key distribution.

Polarization modulation plays a key role in polarization-encoding quantum key distribution (QKD). Here, we report a new, to the best of our knowledge, polarization modulation scheme based on an inherently stable Sagnac interferometer. The presented scheme is free of polarization mode dispersion and calibration as well as insensitive to environmental influences. Successful experiments at a repetition frequency of 1.25 GHz have been conducted to demonstrate the feasibility and stability of the scheme. The measured average quantum bit-error rate of the four polarization states is as low as 0.27% for 80 consecutive minutes without any adjustment. This high-speed intrinsically stable polarization modulation can be widely applied to many polarization-encoding QKD systems, such as BB84, MDI, etc.

Point-ahead demonstration of a transmitting antenna for satellite quantum communication.

A low-divergence beam is an essential prerequisite for a high-efficiency long-distance optical link, particularly for satellite-based quantum communication. A point-ahead angle, caused by satellite motion, is always several times larger than the divergence angle of the signal beam. We design a novel transmitting antenna with a point-ahead function, and provide an easy-to-perform calibration method with an accuracy better than 0.2 µrad. Subsequently, our antenna establishes an uplink to the quantum satellite, Micius, with a link loss of 41-52 dB over a distance of 500-1,400 km. The results clearly confirm the validity of our model, and provide the ability to conduct quantum communications. Our approach can be adopted in various free space optical communication systems between moving platforms.

Satellite-Relayed Intercontinental Quantum Network.

We perform decoy-state quantum key distribution between a low-Earth-orbit satellite and multiple ground stations located in Xinglong, Nanshan, and Graz, which establish satellite-to-ground secure keys with ∼kHz rate per passage of the satellite Micius over a ground station. The satellite thus establishes a secure key between itself and, say, Xinglong, and another key between itself and, say, Graz. Then, upon request from the ground command, Micius acts as a trusted relay. It performs bitwise exclusive or operations between the two keys and relays the result to one of the ground stations. That way, a secret key is created between China and Europe at locations separated by 7600 km on Earth. These keys are then used for intercontinental quantum-secured communication. This was, on the one hand, the transmission of images in a one-time pad configuration from China to Austria as well as from Austria to China. Also, a video conference was performed between the Austrian Academy of Sciences and the Chinese Academy of Sciences, which also included a 280 km optical ground connection between Xinglong and Beijing. Our work clearly confirms the Micius satellite as a robust platform for quantum key distribution with different ground stations on Earth, and points towards an efficient solution for an ultralong-distance global quantum network.

Experimental free-space quantum key distribution with efficient error correction.

We report a 17-km free-space quantum key distribution (QKD) experiment using an engineering model of the space-bound optical transmitter and a ground station for satellite-ground QKD. The final key rate of ~ 0.5 kbps is achieved in this experiment with the quantum bit error rate (QBER) of ~ 3.4%. An efficient error correction algorithm, Turbo Code, is employed. Compared with the current error correction algorithm of Cascade, a high-efficiency error correction is realized by Turbo Code with only one-time data exchange. For a low QBER, with only one-time data exchange, the final key rates based on Turbo code are similar with Cascade. As the QBER increases, Turbo Code gives higher final key rates than Cascade. Our results experimentally demonstrate the feasibility of satellite-ground QKD and show that the efficient error correction based on Turbo Code is potentially useful for the satellite-ground quantum communication.

Satellite-to-Ground Entanglement-Based Quantum Key Distribution.

We report on entanglement-based quantum key distribution between a low-Earth-orbit satellite equipped with a space borne entangled-photon source and a ground observatory. One of the entangled photons is measured locally at the satellite, and the other one is sent via a down link to the receiver in the Delingha ground station. The link attenuation is measured to vary from 29 dB at 530 km to 36 dB at 1000 km. We observe that the two-photon entanglement survives after being distributed between the satellite and the ground, with a measured state fidelity of ≥0.86. We then perform the entanglement-based quantum key distribution protocol and obtain an average final key rate of 3.5 bits/s at the distance range of 530-1000 km.

A 1.25-GHz multi-amplitude modulator driver in 0.18 µm SiGe BiCOMOS technology for high speed quantum key distribution.

Quantum key distribution (QKD) research has yielded highly fruitful results and is currently undergoing an industrialization transformation. In QKD systems, electro-optic modulators are typically employed to prepare the required quantum states. While various QKD systems operating at GHz repetition frequency have demonstrated exceptional performance, they predominantly rely on instruments or printed circuit boards to fulfill the driving circuit function of the electro-optic modulator. Consequently, these systems tend to be complex with low integration levels. To address this challenge, we have introduced a modulator driver integrated circuit in 0.18 µm SiGe BiCMOS technology. The circuit can generate multiple-level driving signals with a clock frequency of 1.25 GHz and a rising edge of ∼50 ps. Each voltage amplitude can be independently adjusted, ensuring the precise preparation of quantum states. The measured signal-to-noise ratio was more than 17 dB, resulting in a low quantum bit error rate of 0.24% in our polarization-encoding system. This work will contribute to the advancement of QKD system integration and promote the industrialization process in this field.

Challenges of phototherapy for neonatal hyperbilirubinemia (Review).

Phototherapy is universally recognized as the first option for treating neonatal jaundice due to its unparalleled efficiency and safety in reducing the high serum free bilirubin levels and limiting its neurotoxic effects. However, several studies have suggested that phototherapy may elicit a series of short- and long-term adverse reactions associated with pediatric diseases, including hemolysis, allergic diseases, DNA damage or even cancer. The aim of the present review was to summarize the etiology, mechanism, associated risks and therapeutic strategies for reducing high neonatal serum bilirubin levels. In order to shed light on the negative effects of phototherapy and to encourage implementation of a reasonable and standardized phototherapy scheme in the clinic, the present review sought to highlight the current understanding of the adverse reactions of phototherapy, as it is necessary to further study the mechanism underlying the development of the adverse effects of phototherapy in infants in order to explore novel therapeutic alternatives.