Statistical Mech cond-mat.stat-mech

A team assembling a jigsaw puzzle from random pieces: how many simultaneous moves does it take to complete the picture? If the pieces are independent, they all go down at once. If each piece depends on the previous one, you have to work one at a time. So it is with systems: some states assemble instantly, others require a long sequential effort.

A crowd in a square. At first, everyone spins to their own rhythm, but suddenly the music changes, and they all start moving in sync, as one. That's roughly how electrons behave in some metals: they either cling to magnetic impurities or break away and form a collective order.

In 1988, the surface temperature of the Pacific Ocean began to change long before meteorologists declared the onset of El Niño. Points on the map scattered along the equator started behaving in concert: if water warmed in one place, it did so in a neighboring one too.

The Paglia River behaves like a pendulum that resists being pushed. If a sudden influx of water pours in, the river does not keep gaining strength but quickly swings back to its usual level. This behavior is called antipersistence, and it was found in a twenty-two-year record of half-hourly discharge measurements near the Italian town of Orvieto.

The speedometer needle in a car shows how fast the wheels are spinning. The climate system also has rotation, but it is invisible: it happens in state space, where each point is a combination of ocean temperature, the depth of the warm layer, and other parameters.

Every June, the sky over India fills with moisture, and how much falls determines rice harvests, water reserves, and food prices for a billion people. But predicting the monsoon's strength in advance was like guessing someone's mood from a single photo: too many hidden springs.

In the Pacific Ocean, every few years the water off the coast of Peru warms up, and fishermen call it El Niño. Sometimes the warming is mild, sometimes so strong that it changes weather across the entire planet. Forecasting a strong El Niño six months to a year ahead is a task at the edge of possibility: weather is forgotten within two weeks, while climate remembers for decades.

Quantum entanglement is like an invisible spring between particles — squeeze one, and the other twitches, no matter where it is. In the new work, physicists built a model of four spins (tiny magnetic arrows) in a chain, where the end spins are held by a local magnetic field.

A fisherman pulls on his net and listens to it ring. Each strand quivers in its own way, but before a strong tug, all the strands begin to vibrate in unison. So it is with complex systems: before a sharp state jump, the individual parts suddenly start to oscillate in concert, and that synchrony betrays the coming jump.

In a chain of eight spins, a defect lurks — a tiny magnetic moment. The Kondo effect, known since the 1930s, makes electrons around it align into a collective screen. The material's resistance abnormally increases. But detecting such an impurity hidden deep in the structure is like finding a stone at the bottom of a dark pond.

The orchestra plays the symphony of climate. Each violin, each wind instrument carries its own part: these are the Kolmogorov modes, the system's natural rhythms. Suddenly, a thunderclap bursts into the hall: a sharp jump, like a gust of wind or a downpour. Previously, we could only listen to the smooth sound, but we couldn't decipher such chords. In the new work, mathematicians have completed the score.

A postal money order doesn't arrive instantly but after a set delay, and the amount credited to the recipient's account ends up larger than what the sender deposited in cash. That's roughly how the new protocol, dubbed temporal quantum energy teleportation (TQET), works. In ordinary quantum energy teleportation, two parties, Alice and Bob, share a common quantum state.

In a chain of cold spins stretched along a single line, order and disorder can intertwine into a pattern that defies the usual rules. Two states of matter, two kinds of "order," are separated by a crossroads where the roads do not converge but diverge.

Five superconducting qubits on a chip: the stage for a performance of quantum chaos. Four qubits form the system, and the fifth acts as the environment, introducing dissipation. After a short evolution, the environment is discarded, leaving the system with an open quantum map, an operator that transforms the system's state.

You can sit on a seesaw and pump your legs, or you can just tip from one side to the other. The Pacific Ocean does both. Every few years, warm water off the coast of Peru gives way to cooler water, and rainfall patterns, winds, and entire ecosystems across half the planet reshuffle. These shifts are called El Niño and La Niña, together known as ENSO: Earth's climate seesaw.

In 1867, James Clerk Maxwell imagined a demon that sorts gas molecules and thereby violates the second law of thermodynamics. The demon needs to know the speeds of the particles. In the quantum world, a similar task arises: keep entanglement from growing like an avalanche, but you cannot observe the entire system.

Two qubits, quantum bits, two-level systems, glide through hot and cold thermal baths. One moves at 0.8 times the speed of light. At that moment, familiar thermodynamics cracks: a moving qubit senses temperature differently than a stationary one. For it, the cold bath can feel hotter, and the hot bath colder.

Quantum entanglement is a fragile resource. Heat a system, and thermal fluctuations will tear the delicate threads of correlations: at a sufficiently high but finite temperature, the Gibbs state of a local Hamiltonian becomes separable, that is, representable as a probabilistic mixture of products of local states.

A stretched string between two quarks doesn't pop instantly like a rubber band. It first vibrates, develops knots, and only then breaks, if it breaks at all. This isn't just a metaphor; it's an accurate description of what physicists call confinement: quarks are permanently locked inside hadrons, and the only way to separate them is to snap the flux tube that binds them.

In the quantum world, noise usually destroys orderly behavior, like random jolts damping a pendulum. But on IBM quantum processors, physicists discovered the opposite: structured noise can prolong and even create rhythmic oscillations. It's like a pendulum that swings harder from seemingly chaotic yet internally synchronized pushes.

Everything tends toward equilibrium: tea cools, a pendulum swings to rest. The measure of this movement is entropy — growing disorder. But sometimes hot water freezes before warm. The Mpemba effect isn't just a curiosity: it shows up in the quantum world too. Scientists have devised a way to control this paradox.

Emptiness isn't always empty: it can hide energy, like supercooled water hides ice. Physicists call this false vacuum — a state that only needs a nudge to cascade into the true one.

To quickly dissolve sugar, you don't need to stir carefully — just shake the glass. A similar principle works in quantum systems: noise, usually considered a disturbance, speeds up the transition to a thermal state.

Paraglider, hang glider, and glider — three different wings, but in the sky they behave the same. Pilots catch invisible warm air currents, rise on them, then glide to the next. Such flight is like a game of hopscotch: a jump upward, then a glide forward, and again a search for a place to jump. Scientists analyzed thousands of real routes and found a common law.

Graphs are considered identical if their 'terrain' matches. Imagine two maps with mountains and valleys: even if drawn differently, the heights and steepness of slopes can be the same.

Our Universe may have arisen from a highly unstable state that physicists call the false vacuum. Imagine a glass of water cooled below its freezing point: the liquid remains liquid only until the first jolt, which instantly triggers crystallization into ice.

Five charged calcium atoms hover in a trap, held by electric fields. Laser cooling saps their excess energy, and they line up into a tiny pyramid with a square base. But this pyramid doesn't stay put: every now and then it flips over, as if someone tosses it into the air and catches it upside down.

Run a current through a wire, and the wire heats up. Anyone who has ever touched a phone charger knows this. Physicists call this heating Joule heating, after James Joule, who in the mid-19th century measured how much heat electricity produces. Since then, the formula has been simple: the greater the resistance and the current, the hotter the wire.

Every machine, whether a car engine or a tiny nanocooler, runs with a jitter. Fuel burns unevenly, electrons slip through contacts off schedule, and the power needle on your instruments vibrates slightly. These vibrations are called fluctuations. They are not just noise: they tell you how stable a device is and how much energy it wastes.

A group of people searches for a lost item in a large park. Some get tired and leave, others join along the way. The number of searchers is constantly changing. How does this affect the search time? Until now, science had no clear answer. In a new study, a general model of such a process has been built. In it, independent participants randomly enter and leave the search.

A quantum computer is like a pot of boiling water: particles are jostling around chaotically, and you need to calm them down to get a useful answer. In a new study, physicists have devised a way to cool a chain of 19 quantum spins (tiny magnets) right on a real device.

A handful of lead sulfide nanocrystals coated with charged molecules spontaneously assembles into a perfect crystalline lattice. Each nanocrystal is like a brick just a few nanometers across, while the charged molecules on its surface act as the mortar.

Shake a jar of sand and marbles, and you'll see large objects float or sink depending on their size. But if you shake it cleverly, you can make the marbles gather into pairs and chains, as if glued together. It's this kind of 'invisible glue' that physicists from India and Germany have now caught and measured for the first time.

A translator who jumps at every rustle in the hall turns a one-hour meeting into two. It's the same in epidemic control: contact tracing teams try to reconstruct the chain of infections, but something always slips through. Someone forgets who they met, someone doesn't answer the phone, someone never even comes to the attention of health workers.

Salt in a glass of water is a crowd of charged particles. When there's plenty of water, each particle floats on its own, wrapped in a thick fur coat of water molecules. But as you keep adding salt, the water runs out for everyone, and the particles start seeking each other out. First, they stick together in pairs, then in larger clumps.

A glass of solidified glass may seem motionless, but inside, the atoms are frozen in random positions, never having found perfect order. A similar situation occurs in spin glasses: the magnetic moments of atoms freeze, pointing in different directions, and the material loses the ability to be simply magnetized.

Temperature seems like something frozen: a substance has a temperature, and that's that. But look closer, and thermal equilibrium resembles a waterfall that appears motionless from the side even though it consists of a continuous stream of water. In the same way, any body at finite energy constantly exchanges photons with its surroundings.

Fourteen rubidium atoms lined up like beads on a string. Each atom is a tiny magnet that can point up or down. Together they follow strict rules, similar to a train schedule: everything is predictable, everything repeats. But introduce a barely noticeable change, and the schedule goes off the rails.

The quantum world is full of surprises: even simply observing a particle changes its behavior. In a new study, physicists showed that continuously measuring energy can make quantum chaos more pronounced. They used a quantity that indicates how long a quantum state remains similar to itself under repeated measurements.

A pot on a stove receives heat, but not work: the gas under the lid just heats up. But what if the stove is not ordinary, but quantum? Then heat and work can arrive simultaneously, like from an engine that also heats. In a new study, exactly this case is described: a classical system (say, a pendulum or a small mirror) bathes in a quantum environment.