Using quantum circuits to investigate transition phases Everyone aimed to simulate in this experiments.
Transition Phases Introduction
A disordered quantum state changing into a long-range ordered state is known as a “phase transition.” Specifically, one can want to realize the Greenberger-Horne-Zeilinger (GHZ) state, which is one of the few well-studied large-scale entangled quantum states and the most basic example of long-range order in quantum systems. The ground state of the random bond Ising model, a simplified representation of magnetism that is frequently employed in physics research and was the model of interest in the IBM Quantum utility experiment in 2023, provides another way to conceptualize the GHZ state.
The first experiment, it should be noted, focused on the transverse-field Ising model, in which spins interact with a magnetic field perpendicular to their alignment. Contrarily, the focus of this experiment is the random bond Ising model, in which the spin system is more likely to reside in a disordered form because of differences in the strength of interactions between the nearby spins.
What is phase transition?
You have seen one firsthand if you have ever watched an ice cube melt into liquid water. The ice molecules enter a sort of transitional stage when they approach melting temperature, where they are basically undecided about whether they want to stay in the ice cube’s rigid crystalline structure or transition into the more chaotic liquid phase of water. A transition phases is the process that converts ice to liquid water.
It is similar to melting and then freezing an ice cube to simulate the GHZ state’s phase shift from long-range order to disorder and back again. However, the GHZ state is composed of “spins” rather than water molecules.
One way to conceptualize a spin in an Ising model system is as a magnet the size of an atom placed in a grid-like structure or “lattice” with other spins to form a bigger magnetic substance. There are two possible directions for the spin to point: up or down.
Physicists are often interested in the conundrum of whether the spins in a lattice want to be aligned or random. The now-famous Nishimori line, found by theoretical physicist Hidetoshi Nishimori in the 1970s, illustrates this transition from order to disorder in spin glass models.
Describe a spin glass. Condensed-matter physics studies a particular kind of magnetic condition called a spin glass. Disorder and haphazard interactions between the system’s constituent spins are its defining features.
Similar to the Ising model for random bonds that was employed in this experiment. The image below is an illustration of this.
As you might expect, a system with all of its spins aligned in either the spin up or spin down state is to be long-range ordered. The system moves from the long-range ordered phase into the disordered phase, following the Nishimori line, as the temperature or disorder probability is raised. The Nishimori transition, also referred to as the Nishimori “criticality,” is the boundary between long-range order and disorder that is indicated in blue in the above picture.
The GHZ condition is indicated by the red point at the bottom of the figure.
To the best of the knowledge, it is impossible to create a really long-range ordered state in a real magnetic material as doing so would necessitate actively adjusting each of the substance’s unique atomic-scale characteristics. There are always minute flaws in real magnets, such as individual atoms whose spins are out of alignment with the system as a whole. nevertheless demonstrated in to Nature Physics experiment that we can mimic the interaction between spins in a lattice using the qubits of an IBM quantum computer. It can then dynamically modify the individual magnets in the lattice to realize the phase transition between disorder and long-range order.
Whether this type of tuning could be carried out in the presence of measurement inaccuracy was unknown until this investigation. Even though these implementation of this transition phases is intrinsically noisy, to research demonstrates that it is possible to manage the spin degree of freedom in qubits in a manner similar to boiling water by providing heat. Everyone were able to accomplish this in a quantum computer.
Uses and Consequences
Condensed matter physics, quantum materials, and developing quantum technologies are all significantly impacted by the knowledge of transition phases via quantum circuits. Deeper understanding of topological phases, superconductivity, and even possible developments in quantum error correction for reliable quantum computing are made possible by it.
In conclusion
In order to better understand quantum-critical phenomena, quantum circuits provide a fresh and efficient method of investigating phase transitions. Researchers can better study intricate quantum phase transitions with the help of continuous improvements in quantum hardware and algorithms, opening the door to novel physics and technological breakthroughs.
