Experts say quantum computing is the future of computers. Unlike conventional computers, quantum computers leverage the properties of quantum physics such as superposition and interference, theoretically outperforming current equipment to an exponential degree.
When a quantum computer is able to solve a problem unfeasible for current technologies, this is called the “quantum advantage.” However, this edge is not guaranteed for all calculations, raising fundamental questions regarding the conditions under which such an advantage exists. While previous studies have proposed various sufficient conditions for quantum advantage, the necessity of these conditions has remained unclear.
Motivated by this uncertainty, a team of researchers at Kyoto University has endeavored to understand the necessary and sufficient conditions for quantum advantage, using an approach combining techniques from quantum computing and cryptography, the science of coding information securely.
An international law enforcement action dismantled a Romanian ransomware gang known as ‘Diskstation,’ which encrypted the systems of several companies in the Lombardy region, paralyzing their businesses.
The law enforcement operation codenamed ‘Operation Elicius’ was coordinated by Europol and also involved police forces in France and Romania.
Diskstation is a ransomware operation that targets Synology Network-Attached Storage (NAS) devices, which are commonly used by companies for centralized file storage and sharing, data backup and recovery, and general content hosting.
Quantum computers have the potential to revolutionize computing by solving complex problems that stump even today’s fastest machines. Scientists are exploring whether quantum computers could one day help streamline global supply chains, create ultra-secure encryption to protect sensitive data against even the most powerful cyberattacks, or even develop more effective drugs by simulating their behavior at the atomic level.
But building efficient quantum computers isn’t just about developing faster chips or better hardware. It also requires a deep understanding of quantum mechanics—the strange rules that govern the tiniest building blocks of our universe, such as atoms and electrons—and how to effectively move information through quantum systems.
In a paper published in Physics Review X, a team of physicists—including graduate student Elizabeth Champion and assistant professor Machiel Blok from the University of Rochester’s Department of Physics and Astronomy—outlined a method to address a tricky problem in quantum computing: how to efficiently move information within a multi-level system using quantum units called qudits.
Understanding randomness is crucial in many fields. From computer science and engineering to cryptography and weather forecasting, studying and interpreting randomness helps us simulate real-world phenomena, design algorithms and predict outcomes in uncertain situations.
Randomness is also important in quantum computing, but generating it typically involves a large number of operations. However, Thomas Schuster and colleagues at the California Institute of Technology have demonstrated that quantum computers can produce randomness much more easily than previously thought.
And that’s good news because the research could pave the way for faster and more efficient quantum computers.
Quantum computers still face a major hurdle on their pathway to practical use cases: their limited ability to correct the arising computational errors. To develop truly reliable quantum computers, researchers must be able to simulate quantum computations using conventional computers to verify their correctness—a vital yet extraordinarily difficult task.
Now, in a world-first, researchers from Chalmers University of Technology in Sweden, the University of Milan, the University of Granada, and the University of Tokyo have unveiled a method for simulating specific types of error-corrected quantum computations—a significant leap forward in the quest for robust quantum technologies.
Quantum computers have the potential to solve complex problems that no supercomputer today can handle. In the foreseeable future, quantum technology’s computing power is expected to revolutionize fundamental ways of solving problems in medicine, energy, encryption, AI, and logistics.
Making the exchange of a message invulnerable to eavesdropping doesn’t strictly require quantum resources. All you need to do is to encrypt the message using a one-use-only random key that is at least as long as the message itself. What quantum physics offers is a way to protect the sharing of such a key by revealing whether anyone other than sender and recipient has accessed it.
Imagine that a sender (Alice) wants to send a message to a recipient (Bob) in the presence of an eavesdropper (Eve). First, Alice creates a string of random bits. According to one of the most popular quantum communication protocols, known as BB84, Alice then encodes each bit in the polarization state of an individual photon. This encoding can be performed in either of two orientations, or “bases,” which are also chosen at random. Alice sends these photons one at a time to Bob, who measures their polarization states. If Bob chooses to measure a given photon in the basis in which Alice encoded its bit, Bob’s readout of the bit will match that of Alice’s. If he chooses the alternative basis, Bob will measure a random polarization state. Crucially, until Alice and Bob compare their sequence of measurement bases (but not their results) over a public channel, Bob doesn’t know which measurements reflect the bits encoded by Alice. Only after they have made this comparison—and excluded the measurements made in nonmatching bases—can Alice and Bob rule out that eavesdropping took place and agree on the sequence of bits that constitutes their key.
The efficiency and security of this process depend on Alice’s ability to generate single photons on demand. If that photon-generation method is not reliable—for example, if it sometimes fails to generate a photon when one is scheduled—the key will take longer to share. If, on the other hand, the method sometimes generates multiple photons simultaneously, Alice and Bob run the risk of having their privacy compromised, since Eve will occasionally be able to intercept one of those extra photons, which might reveal part of the key. Techniques for detecting such eavesdropping are available, but they involve the sending of additional photons in “decoy states” with randomly chosen intensities. Adding these decoy states, however, increases the complexity of the key-sharing process.
Quantum computers can solve extraordinarily complex problems, unlocking new possibilities in fields such as drug development, encryption, AI, and logistics. Now, researchers at Chalmers University of Technology in Sweden have developed a highly efficient amplifier that activates only when reading information from qubits. The study was published in the journal IEEE Transactions on Microwave Theory and Techniques.
Thanks to its smart design, it consumes just one-tenth of the power consumed by the best amplifiers available today. This reduces qubit decoherence and lays the foundation for more powerful quantum computers with significantly more qubits and enhanced performance.
Bits, which are the building blocks of a conventional computer, can only ever have the value of 1 or 0. By contrast, the common building blocks of a quantum computer, quantum bits or qubits, can exist in states having the value 1 and 0 simultaneously, as well as all states in between in any combination.
Quantum key distribution (QKD), a cryptographic technique rooted in quantum physics principles, has shown significant potential for enhancing the security of communications. This technique enables the transmission of encryption keys using quantum states of photons or other particles, which cannot be copied or measured without altering them, making it significantly harder for malicious parties to intercept conversations between two parties while avoiding detection.
As true single-photon sources (SPS) are difficult to produce, most QKD systems developed to date rely on attenuated light sources that mimic single photons, such as low-intensity laser pulses. As these laser pulses can also contain no photons or more than one photon, only approximately 37% of pulses employed by the systems can be used to generate secure keys.
Researchers at the University of Science and Technology of China (USTC) were recently able to overcome this limitation of previously proposed QKD systems, using a true SPS (i.e., a system that can emit only one photon on demand). Their newly proposed QKD system, outlined in a paper published in Physical Review Letters, was found to outperform techniques introduced in the past, achieving a substantially higher secure key rate (SKR).