Will colour molecules make quantum computers accessible (GS Paper 3, Science and Technology)
Why in news?
- In a recent collaborative study by a group of institutions in Japan, researchers realised qubits at room temperature in a metal-organic framework (MOF).
- A MOF is a network of repeated molecular arrangements where the repeating structure has a metal atom or ion with organic molecules attached to it like tentacles. Each tentacle attaches to another metal atom, and the structure repeats itself to make up the MOF.
Qubits:
- A classical computer is a collection of information storage units called bits. These physical devices have two states each, denoted 0 and 1. Any computation that a computer performs is essentially the result of the manipulation of the states of bits.
- Similarly, a qubit is a physical system with two quantum states, and it is the fundamental physical component of a quantum computer. A qubit can exist in one of the two states or a superposed state with contributions from both states.
- This superposition is a quantum feature that the bits in conventional computers don’t exhibit. Superposed states, also known as coherent superpositions, are important in quantum information-processing protocols. However, superpositions are fragile.
- The fragility arises out of the interaction between the qubit and other systems. The more the number of interaction channels, the faster the superposition “decoheres” and the qubit ends up in one of the two states.
Conditions for realising qubits:
- A collection of qubits is required to make a quantum device. For this, any group of qubits needs to satisfy a few basic requirements.
- The qubits should be identical. The qubits can’t be guaranteed to be identical since they need to be manufactured, and some ‘imperfections’ will creep in.
- It should be relatively easy to integrate several qubits that can be operated controllably. Here, controllability refers to both the manipulation of individual qubits (a.k.a. “addressability”) and qubit-qubit interactions.
- An important, related aspect is the qubit system should be robust enough to function at room temperature without losing quantum features for reasonably long durations.
- Many different physical systems are suitable for realising qubits. Some well-studied and practical options include superconducting junctions, trapped ions, and quantum dots. However, all these systems can operate as qubits only at very low temperatures or in a high vacuum or both.
- In some cases, like superconducting junctions, a low temperature is in fact essential for them to work as qubits. In other cases, a low temperature is required for quantum features like superposition to survive for longer in the computer.
Recent research:
- In the system studied by the Japanese team, zirconium is the metal component and an organic molecule containing the chromophore pentacene bridges the metal atoms. A chromophore is an organic molecule or a part of a larger molecule that absorbs light of some specific colour.
- An object containing such molecules thus appears to have some dominant colour. For example, the leaves of many plants appear green since the chromophore chlorophyll predominantly absorbs red and blue colours from sunlight. Since the presence of chromophores is responsible for the colouration, they are also called “colour molecules”.
- When it absorbs light, the chromophore molecule jumps to a higher energy level (i.e. an excited state).
- In its lowest energy state, or ground state, a chromophore molecule has a pair of electrons in a special configuration called a singlet. Every electron possesses a property called spin that is inherent to it. The spin of an electron can point in two opposite directions, each corresponding to a distinct quantum state.
Role of singlet fission:
- An excited molecular system has a small but non-zero chance of releasing its extra energy in a process called deexcitation. The higher energy singlet excited state can deexcite to a lower energy triplet excited state. The energy released in the process will excite a neighbouring chromophore molecule in a singlet ground state to jump to a triplet excited state.
- This process of generating two triplet excited chromophores from a singlet excited state chromophore is called singlet fission. This energy transfer happens as the two chromophores interact.
- The MOF networks are very porous, like sponges, allowing the chromophores to rotate by a small degree.
Triplet state:
- The rotation leads to a change in the interaction strength between two adjacent chromophores.
- The triplet state of one of the chromophores involves two of its energy levels (recall the ladder-rung analogy), and that of the other chromophore involves two energy levels in its own energy ladder.
- The interaction between the chromophores prepares the two pairs of electrons in a superposition wherein each pair is in a triplet state. The rotation-induced modulation also seems to play a role in ensuring the superposition of triplet states generated by singlet fission is long-lived.
Outcome:
- The interaction between the chromophores is strong enough to cause singlet fission but weak enough to not allow the coherence to be lost once the triplets form.
- In their experiment, the Japanese team found that even at room temperature, the coherence of the superposition of two four-electron states survived up to a fraction of a microsecond, which is a long duration in the current context. Other qubit systems require an extremely low temperature if coherence has to last this long.
Way Forward:
- It remains to be seen whether researchers can demonstrate how to achieve quantum gate operations on these qubits, assemble several qubits, and achieve controllability.
- Nevertheless, the availability of room-temperature qubits is a significant achievement that will invite many research groups to explore the system further.
Russia economy after two years of war
(GS Paper 2, International Relation)
Context:
- Two years after its full-scale invasion of Ukraine, Russia is still facing an unprecedented number of economic sanctions.
Impact of economic situations:
- It has been excluded from major global financial services, and around €260 billion (£222 billion) of its central bank assets have been frozen. Russian airspace is closed to most western planes, and western ports are closed to Russian vessels.
- A formal cap has been imposed on buying or processing Russian oil sold for more than $60 per barrel (world prices currently fluctuate between $80 and $100). And in theory, it is illegal to sell Russia anything that could be used by the military.
- Sanctions have had some effects. According to the IMF, Russia’s GDP is around 7% lower than the pre-war forecast.
Resilience in Russia’s economy:
- It is now entirely focused on a long war in Ukraine which is actually driving economic growth. In fact, the IMF expects Russia to experience GDP growth of 2.6% in 2024. That’s significantly more than the U.K. (0.6%) and the EU (0.9%).
- Similarly, Russia’s budget deficit (the amount the government needs to borrow) is on track to remain below 1% of GDP, compared to 5.1% in the U.K. and 2.8% in the EU. One reason for this relative resilience is Russia’s strong, independent central bank. Since 2022, it has imposed massive interest rate hikes (currently at 16%) to control inflation (still above 7%).
- This has been combined with government-imposed controls which make it almost impossible for Russian exporters and the many foreign companies still operating in Russia to take money out of the country. Together, these policies have helped to avoid a total collapse of the ruble, by keeping the currency flowing inside Russia.
Circumvention of sanctions:
- Russian firms have also learned to sidestep sanctions, with the oil cap being a prime example. In theory, no Russian oil should be traded with the west above the cap, which would have a massive impact on Russia’s public finances.
- In practice, it has been circumvented by a large “dark” fleet of uninsured vessels and the use of accounting loopholes. And while sanctioning countries are trying to tighten the rules, Russia’s public coffers have actually been flooded with oil money. Many countries have also made money playing the role of intermediaries.
- Turkey, China, Serbia, Bulgaria and India are among those which have reportedly circumvented sanctions, and carried on selling goods to Russia. Those products are understood to often include dual-use goods such as microchips or communication equipment that are subsequently used by the Russian military.
- Despite recent efforts, a full regime of extra-territorial trade sanctions is still far away.
Fortunes of war:
- The most worrying reason for the Russian economy’s resilience is the war itself. For a long time, the economy of Russia has not been diverse, relying heavily on the export of natural resources such as oil and gas.
- A major reason for the relatively high revenue of the Russian government today is precisely that the war has led to high energy prices. Russia’s public spending is at unprecedented levels, and around 40% of the government budget is spent on the war. Total military spending is expected to reach more than 10% of GDP for the year 2023 (the U.K. figure is 2.3%).
- Military pay, ammunition, tanks, planes, and compensation for dead and wounded soldiers, all contribute to the GDP figures. Put simply, the war against Ukraine is now the main driver of Russia’s economic growth. And it is a war that Russia cannot afford to win.
Conclusion:
- A protracted stalemate might be the only solution for Russia to avoid total economic collapse. Having transformed the little industry it had to focus on the war effort, and with a labour shortage problem worsened by hundreds of thousands of war casualties and a massive brain drain, the country would struggle to find a new direction.
- Thirty-five years after the fall of the Berlin Wall, it has become clear that resource-rich Russia has become much poorer than its former Soviet neighbours such as Estonia, Latvia, Poland and Hungary, who pursued the route of European integration.
- The Russian regime has no incentive to end the war and deal with that kind of economic reality. So it cannot afford to win the war, nor can it afford to lose it. Its economy is now entirely geared towards continuing a long and ever deadlier conflict.
What is Bitcoin halving and what does it mean for the crypto community?
(GS Paper 3, Economy)
Why in news?
- Crypto traders and Bitcoin miners are preparing for the ‘Bitcoin halving’predicted to happen in April.
What is the Bitcoin halving?
- Bitcoin halving refers to the 50% reduction in the reward paid to Bitcoin miners who successfully process other people’s cryptocurrency transactions so that they can be added to the public digital ledger known as the blockchain.
- In order to “grow” Bitcoin’s blockchain and keep the ecosystem running, Bitcoin miners rely on advanced computer equipment to solve a complex mathematical puzzle through a process known as ‘Proof of work.’ This intense activity is the reason Bitcoin transactions result in huge carbon footprints and require vast amount of electricity. No real mining is carried out.
- The Bitcoin miners with cutting-edge computer equipment, working on an industrial scale, are most likely to solve the puzzle first and claim their prize, which is currently set at 6.25 Bitcoin (BTC).
- While the reward amount is set, the true value of this prize fluctuates based on BTC prices in the market, and when the owner chooses to sell.
Why does the Bitcoin halving matter to crypto investors?
- Bitcoin mining increases the supply of BTC in circulation while Bitcoin halving reduces the rate at which these coins are released, making the asset more scarce.
- Scarcity is seen as pushing up prices, as is the case with gold. While there can only ever be 21 million BTC in the world, over 19 million have already been “mined” or released.
- A halving takes place after 2,10,000 blocks are mined, and has happened so far in 2012, 2016, and 2020 — every four years.
- In 2009, a successful Bitcoin miner could claim a prize of 50 BTC. After this year’s halving, they will only get 3.125 BTC. However, keep in mind that Bitcoin prices are far higher now than they were in 2009, so this isn’t necessarily a loss for the miner.
- Both corporate and independent Bitcoin miners are spread across the world, trying to leverage cheap electricity prices in countries like Kazakhstan and Iran to mine as much Bitcoin as they can. China was originally home to many of the world’s crypto miners, but government crackdowns triggered an exodus to other countries.
Way Forward:
- Every halving in Bitcoin’s history has been wildly different due to an eclectic mix of blockchain-related factors, increasing regulation by lawmakers worldwide, more awareness about cryptocurrency investments, greater adoption of Bitcoin, and diverse geopolitical events or economic shocks.
- Bitcoin is an asset whose price is largely steered by investors’ emotions, with there even being a ‘Fear and Greed’ indicator to help investors understand how prices could suddenly shift.
- While the next Bitcoin halving will be a fascinating episode to witness, it is best for crypto watchers to rely on their own research and decide what the halving means to them personally.
