Tag Archives: Quantum Computation

Two Top Scientists Find The Existence of a Soul Through Quantum Theory

Yeah, it makes everyone a scientist and also provides good headline fodder for journalists. Plus, it’s great for many ‘spiritual leaders’ as they see it as a vindication of their position; something that they have been asserting all along just got some scientific backing. Unfortunately for them, it’s not all that clear cut. Dr. Stuart Hameroff, Professor Emeritus and the Director of the Center of Consciousness Studies at the University of Arizona, and the world renowned physicist and mathematician, Sir Roger Penrose, join forces to forward a new theory – the theory of quantum consciousness.

Carrying the weighty soul?

Quantum what?

You might have already heard of that term, but not yet grasped its meaning. Leave aside all the terrible jargon that is thrown around when ‘spiritual teachers’ like Deepak Chopra speak on this subject, ‘quantum consciousness’ refers to the idea that the brain is a quantum computer and that our consciousness is related to the state of quantum information in our brains. Okay, that might be too much ‘quantum’ for you, so let’s break that up.

Okay… Quantum Mechanics (and Quantum Computers)

Quantum theory, as physicists understand it, has weird elements. It says that particles can be in a superposition of energies, rather than have one fixed energy, can have a ‘spread out’ position, rather than one pinpoint location and that two systems, spatially separated from one another, might still be able to ‘communicate’ with each other, if they were linked to begin with. It’s the last phenomenon that we shall discuss.

The idea is one of ‘coherence’. When two systems are quantum mechanically linked, or ‘entangled’, then measuring one affects the other instantaneously, violating the intuitive concepts of Einstein’s relativity. So if a system A is entangled to system B, measuring A will affect B, no matter how far B is from A, be it half the universe away. This instantaneous change of state has been hypothesized to be useful in making quantum computers.

In a quantum computer, information is stored in energy levels, and since there are more than two energy levels, the two-bit limitation of a normal computer is washed away. We can store much more information. Now, we can perturb a part of the system and, immediately, some other part of the system will be affected. This will help in fast computation, as series computations will take much lesser time.

Of course, for a machine to behave as a quantum computer, the two systems mentioned, say A and B, must remain ‘coherent’. If they disentangle, then they no longer form a quantum computer. Typically, there is a ‘decoherence time’, the typical time required for two entangled systems to disentangle.

And now… Quantum Consciousness!

Now, on to what Penrose and Hameroff are claiming. They claim that inside the neurons, there are tiny structures called microtubules. Information in these microtubules is what constitutes the ‘soul’ or our ‘consciousness’. They go further. Say the body dies. The microtubules lose their quantum state, but retain the quantum information (and information cannot be lost). Thus, the soul remains and is dissipated in the universe at large. This conforms to the eastern position of spirituality which says that the body is mortal, but the soul isn’t and there is a cycle of births.

Penrose and Hameroff dodge the cycle of births and cater to another popular public fascination – near death experiences. They say that the information can be restored into a microtubule if a dying patient is resuscitated and this is what they might feel as a ‘near death experience’.

Spreading the message? Or just spreading pseudo-science?

The theory has gained worldwide popularity owing to a documentary ‘Through a Wormhole’ narrated by Morgan Freeman, aired in the US on the Science Channel.

Quantum… sorry, plain rubbish – the damning rebuttal

At first glance, all of this sounds like hogwash and it probably will sound like that even when you hear it for the 42nd time. The problems are manifold and the scientific community overwhelmingly lines up against this quantum soul theory. Leave alone the fact that microtubules have not been found or that the quantum information dissipation can never be demonstrated or falsified. (Remember that these two are the major tenets of the theory and I am chucking these away!) Max Tegmark, in this paper, deals a severe blow to the quantum soul theory citing the fact that neurons and neural networks behave like classical systems. They aren’t quantum to begin with.

Shall we say that one more time? Yes, neurons and neural networks behave like bouncing tennis balls or moving buses, i.e. they obey laws of classical mechanics and quantum mechanics needn’t be invoked to explain them! Forget about being a quantum computer, these neurons are not even quantum mechanical! Just for fun, Tegmark quotes the typical ‘decoherence time’ (definition above) for these neurons. He notes that these are of the order of 10-13 s to 10-20 s, much much smaller than what’s needed for a quantum computer (~ 10-3 s). Okay, so even if the neurons were quantum objects, they would never form a quantum computer!

So much for the soul. There is still no evidence that it exists. May it rest in a quantum of peace!

Chinese Researchers Teleport Entangled States Through Nearly 100 Km!

The spooky action-at-a-distance just got a lot longer – over six times longer. Though, the phenomenon is not yet ‘Beam me up, Scotty’, the improvement is heartening. A team of Chinese researchers have teleported qubits across a distance of 97 kilometers, using the phenomenon of entanglement.

The spooky entangled world

Entanglement is a purely quantum-mechanical phenomenon, which started on its road to stardom and fame within the physics community and outside it due to a thought experiment by Einstein.

Here it is in simple terms and closely in the same spirit as Einstein, Podolsky and Rosen had first put it. Take two electron. Now, if they are in the same quantum state, one has to be in an ‘up’ spin state and the other in a ‘down’ spin state. The two spins cannot be the same, because another fundamental principle of quantum mechanics – the Pauli exclusion principle – forbids that. Now, take one electron and separate it from the other by a very large distance – say half the universe – but without ever ‘looking’ at it to see what spin state it is in. Now, take the electron near you and look at it to determine what the spin is. But if you know that, you immediately know what spin state the other electron is in! In other words, you get the information about the farther electron instantaneously, violating the fundamental postulate of relativity which forbids the transfer of information faster than light speed.

To EPR or not to EPR

There has been plenty of debates on this so-called EPR paradox. It remained a thought experiment until Alain Aspect and his group actually performed the experiment and found that entanglement is a very real phenomenon. That hasn’t doused the debates though, with people trying to determine what information actually means and whether information is actually transferred.

Photons entangled

Now, the Chinese team uses photons, just like Alain Aspect’s team did in their pioneering experiment. They created two entangled photons, using a 1.3 watt laser, and made them appear at two distinct places separated by as much as 97 kilometers!

Now, a photon can represent a quantum state – or a number of quantum states, really – and can thus be thought of as a ‘qubit’ or quantum bit. It carries a ‘bit’ of information, just like a ‘bit’ on the hard disk of a computer. So far, the researchers have been able to transmit the ‘key’ to a encrypted message, but the message itself needs to be sent via classical channels. It’s like mailing a locked treasure-chest and sending the key to the lock via a quantum mechanically entangled channel.

The work has just been put on ArXiv and here is the link: http://arxiv.org/abs/1205.2024

Scientists Entangle Diamonds Using Vibrations

It seems that Einstein’s spooky action at a distance’ can manifest itself on a macroscopic scale and set two disparate diamonds into entangled’ vibrations. Physicists at University of Oxford, UK, have demonstrated that even diamonds can be quantum mechanically entangled, something that had troubled Einstein deeply as early as the 1930’s.

Diamonds vibrating in sync. Courtesy: Nature communications

What is Entanglement?

Entanglement between two states means that if you alter one state, then the other state automatically responds to it. A simplified version of the entanglement problem was put forward by Einstein, Podolosky and Rosen (EPR) in 1933 and goes like this. If we took two electrons in an orbit, their spin would necessarily be opposite. If one was spinning up, the other would be spinning down. Now, if you separate the two electrons, without ever observing them, by very large distances Einstein said, half the length of the known Universe then, if you observe one, you would automatically know about the spin state of the other. Say, you observe your electron to be in the spin-up state. Since the other electron has to be in the other spin state, it will be in the spin-down state. You’d know this instantly! In other words, you have just transferred information about an electron half the way into the Universe instantly! This is in blatant conflict with Special Relativity. The phenomenon is so detestable, that Einstein compared it with voo-doo, thus coining the phrase Spooky action at a distance’.

Several attempts have been made to make sense out of this. The most respectable argument is that information is not really being transferred. The EPR paradox has also been tested in the laboratory, using entangled photons. Every time quantum mechanics seems to triumph and physicists remain as puzzled as Einstein.

The Present Experiment

In this latest attempt the Oxford group, led by Ian Walmsley, entangled vibrations in a diamond crystal. They fired a laser pulse at two diamonds separated by 15 cm. Each of the pieces were 3 mm wide. The laser would induce vibrations inside the crystals, giving off particles called phonons’, which are quanta of vibrations. The team claims that the disturbance spans 1016 atoms, which makes the vibrating area visible even without a microscope.

Here’s the crucial point! You cannot know which crystal is vibrating, unless you observe them. Automatically, you know something about the other crystal.

The Experimental Work Done – Exciting vibrations

This is how the experimentalists went about their job. They fired a laser at a beam splitter. This, true to its name, split the beam into two. One photon cannot be split up and has to go to either one of the crystals. Once there, it excites a phonon (i.e. induces a vibration). Since, we did not know which crystal the photon had gotten into, the photon was entangled. Once it transfers part of its energy to the phonon, the crystal can emit a low energy photon. This is what is detected and this signals that a phonon has been created. Since, we do not know which crystal the phonon is created in, the crystals are entangled.

Detecting where it came from!

In order to know which crystal is vibrating, the team fired another laser beam at the crystals. This draws out the phonon energy and leaves the crystal as it was before the first laser was fired. The light emitted must have a frequency greater than the one sent in. Scientists arranged for two detectors, one for each crystal, to detect the photons. We would expect 50% chance for each of the the detectors to go off, but what is observed is that the two crystals behave as if they were one entity. Only one of the detectors go off at a time!! They are entangled.

The results were reported in a paper in Nature published today, i.e. on the 2nd of December.

More info here:  http://www.nature.com/news/entangled-diamonds-vibrate-together-1.9532

First Quantum Implementation of Von Neumann Architecture Achieved, Large Quantum Computers Next Stop!

The first quantum version of the Von Neumann architecture has been implemented by physicists at University of California, Santa Barbara (UCSB). This represents a crucial step in the creation of quantum computers which will make calculations at least a million times faster. The micro quantum computers are already here!

The implementation of the von Neumann machine on the quantum scale. Courtesy: UCSB

Why such a big deal?

Kindly realise the magnitude of the achievement. The Von Neumann architecture, partly developed and articulated by mathematical genius John von Neumann, is the principal methodology used in building the hardware and supporting software in computers. The architecture came into existence in the 1940’s due to the work of Von Neumann and Alan Turing. Since then, it has formed the bedrock of computer hardware design, even though there have been many improvements on it. However, the architecture has been realised only with classical computers, or computers whose bits are macroscopic physical objects. It has been a major challenge for computer scientists to either build up the quantum analogue of the Von Neumann architecture or to implement using quantum systems.

What is the Von Neumann Architecture?

Here’s what the Von Neumann architecture is. Every Von Neumann machine is made up of four units the Arithmetic-Logic Unit, the Memory, the Control Unit and the Interface. The architecture prescribes that instructions be also stored in the memory, rather than just data. In fact Von Neumann prescribes that the instruction code be stored exactly like data. In response to the code, the data changes and produces intermediate computation results, finally ending up with the end result. The key feature is that the instructions themselves be pliable. They should change with the data i.e. they are self-modifying. They can be encoded in numeric form, just like data, so that this can be achieved. These instructions are then pulled’ up from the memory. Two types of buses’ or data trains link the various components of the Von Neumann machine the data bus and the address bus. The rate at which these buses can transfer data puts a theoretical upper cut-off. This is the von Neumann’ bottleneck.

Realise that the Von Neumann architecture is contradictory to the structure of modern high level languages, where you have definite separation of the data and the instruction code.

Quantum Implementation: Using Qubits

The circuits developed by the UCSB physicists use superconducting quantum circuits, which require extremely low temperatures to operate. The demonstration of the fact that this can be done implies that quantum computing can indeed be achieved on a macroscopic scale. Dreams of Large Scale Integration (LSI) or Very Large Scale Integration (VLSI), achieved long ago with conventional computer components, are not very far-fetched either!

VLSI on the quantum scale?

The key to the quantum implementation of the Von Neumann architecture is quantum bits or qubits. Unlike the classical bit, which can be in either 1 or 0 state, qubits can exist in a superposition of many quantum states, allowing for many more calculations to be done on a single qubit simultaneously. The fundamental unit of a quantum computer comprises two qubits, a quantum communication bus, two bits of quantum memory and a resetting counter. This uses Von Neumann architecture on the nano scale!

The aim of simultaneously writing information to the quantum memory and performing quantum calculations on the qubit has not been achieved, but scientists are close to that. The three-qubit Toffoli gate has already been implemented.

Super-fast calculations, here we come!

Scientists Achieve First Ever Quantum Teleportation Of Photons: Quantum Computers Coming Soon?

Researchers from Australia and Japan have recently reported a successful attempt at quantum teleportation of a complex quantum system from a certain point A to another point B without losing information. The team was led by scientists from the University of Tokyo, in the lab of Professor Akira Furusawa. This leads to the possibility of achieving fast, high-fidelity transmission of huge chunks of data, all at once, thus revolutionising the current data transportation scenario and providing a boost to the ongoing research on quantum computers.

Quantum Teleportation

Schrodinger and his Cat

The Schrodinger Cat paradox appeared in 1934 and was proposed by Erwin Schrodinger, one of the founders of quantum theory. This thought experiment (‘gedankenexperiment‘) consists of the following setup: A cat is kept in an opaque box with a sealed glass chamber inside it, containing poisonous gas. The glass can be broken by a hammer, which is itself triggered by the decay of a radioactive atom. Since the decay of any radioactive atom is governed by quantum laws and is, thus, entirely probabilistic, no one can say whether the cat is alive or dead with absolute certainty. The answer, however, becomes obvious when one looks into the box. Before the observation, one is forced to conclude that the cat is dead and alive at the same time; it is in a superposition of dead’ and alive’ states. Thus, observation changes the system irreversibly; scientists call it collapse’.

Schrodinger's Cat
Schrodinger's Cat (Image from Wikipedia)

Whereas quantum superposition and collapse are well-accepted by physicists, applying them to macroscopic objects like cats instead of quantum particles makes the situation very strange. The strangeness enticed Schrodinger enough to propose this paradox.

Teleportation, Qubits and the Quantum Computer

The concept of superposition is employed in quantum computers. Unlike a conventional computer, where one bit can have the value 0 or 1, a quantum bit (or qubit) can be in a superposition of the two values. Thus, when there are N bits it represents only one state, where N qubits represent 2N states at once. This greatly augments both speed and volume of computations.

The main problem in achieving quantum computers is that the qubits are highly susceptible to external influences. As discussed above, observing a qubit (i.e. any interaction with the environment) will collapse it into one of the many states that it represents. Thus, a number of qubits cannot be stacked up at a place, unlike computer bits. (Currently, 10 qubits have been ‘stacked’ up.)

Another phenomenon used is that of quantum entanglement. If two states are conjoined at some time, then the observation on one of the states influences the other, even though the latter is not being directly observed. This finds a (hitherto hypothetical) application, which involves performing one operation on a certain part of the computer and, thus, influencing a separate entangled operation. This concept can be exploited in quantum cryptography.


The Japanese team of researchers have successfully teleported a macroscopic system of photons (particles of light), whose phases were superposed.

Are quantum computers just round the corner?