Towards a more efficient quantum ‘hard drive’

Quantum computers encode information in qubits (the basic unit of quantum information) that can not only represent a 0 or a 1 like the bits of ordinary computers but can also use infinite possible combinations of several 0s and 1s. In a quantum computer, a qubit is physically realised with a two-state (or two-level) quantum mechanical system, which serves as the basic quantum switch.

Quantum computers promise to solve complex problems that are currently beyond the reach of classical computers. But quantum systems, on which qubits are based, are incredibly sensitive to temperature variations, electromagnetic interference, and other environmental factors. Even tiny disturbances to a qubit’s delicate quantum state can result in lost data and errors. One of the major challenges in realising practical quantum computing is, therefore, the need for robust error correction mechanisms.

Now, two University of Sydney (UoS) quantum information researchers, Dominic Williamson and Nouédyn Baspin, have developed new architecture to manage errors. Their work was published in a recent issue of Nature Communications.

“There remain significant barriers to overcome in the development of a universal quantum computer,” the lead author Williamson of the UoS’ Nano Institute and School of Physics said in a statement. “One of the biggest is the fact we need to use most of the qubits to suppress the errors that emerge as a matter of course within the technology. Our proposed quantum architecture will require fewer qubits to suppress more errors, liberating more for useful quantum processing,” he added.

Error correction in quantum computers is performed by writing code that operates through the 3D qubit structure, a latticework of how the “quantum switches” are organised. The error correction architecture currently in use works in just one dimension along a single line of connected qubits. The objective is to use as few qubits as possible to reduce errors as they emerge.

At the heart of the new theoretical architecture is a 3D structure that allows for quantum error correction across two-dimensions. “Current 3D codes in a block of dimensions L x L x L can only manage L errors. Our codes can handle errors that scale like L2 (L× L), a significant improvement,” Williamson explained.

Traditional quantum error correction methods, such as the widely studied surface code, have limitations in terms of scalability and resource efficiency. By significantly reducing the number of physical qubits needed for error correction, the Sydney researchers have paved the way for more efficient and compact “quantum hard drives” to achieve scalable quantum computers.

Intense BP lowering in diabetes patients reduces risk of heart attacks

A person living with type 2 diabetes is twice as likely to have high blood pressure (BP) than someone without the condition. Elevated blood sugar levels can cause damage to blood vessels and impair kidney function, leading to elevated BP. Almost three-fourths of adults with type 2 diabetes are estimated to also have high BP, according to data from the US Centers for Disease Control and Prevention. If unmanaged, high BP can cause damage over time and increase the risk of heart attack, stroke, heart failure, kidney problems, and more. High systolic BP (pressure on the artery walls when the heart beats) as against diastolic BP (pressure between beats) is said to be more indicative of cardiovascular risk.

A work presented at the American Heart Association’s Scientific Sessions 2024 recently held in Chicago found that an intensive treatment approach to lowering high systolic BP in people with type 2 diabetes led to a reduced risk of cardiovascular events compared with a standard treatment approach.

“We found that for most people with type 2 diabetes, lowering systolic BP to less than 120 mm Hg reduced the risk of major cardiovascular events,” said the study’s lead author, Guang Ning of Ruijin Hospital at the Shanghai Jiao Tong University School of Medicine.

In the BP Control Target in Diabetes (BPROAD) Study in China, approximately half of the subjects received aggressive treatment to lower their systolic BP to less than 120 mm Hg, and the other half received treatment to lower it to less than 140 mm Hg. During a follow-up period of up to five years, participants in the more intensive treatment regimen had a decreased risk (21 per cent) of major cardiovascular events, including non-fatal stroke, non-fatal myocardial infarction, treated or hospitalised heart failure, and cardiovascular death.

In all, the study enrolled 12,821 adults (average age 64, 45 per cent women and 55 per cent men) with type 2 diabetes, elevated systolic BP, and an increased risk of cardiovascular disease at 145 study sites located in 25 provinces or municipalities across mainland China. Elevated systolic BP was taken as 140 mm Hg without antihypertensive medications or 130 mm Hg if taking at least one antihypertensive medication.

“Our study results are consistent with another study of patients with hypertension but without diabetes, which found a significantly 27 per cent reduction in the incidence of cardiovascular diseases,” said Ning. “Future clinical practice guidelines will hopefully consider these results when making recommendations for blood pressure targets for people with type 2 diabetes,” he said.

Climate change hits new records: Lancet report

The world is facing unprecedented risks to well-being, health, and survival due to climate change, according to a recent report published by Lancet Countdown.

The report, produced after eight years of monitoring with contributions from 122 researchers from UN agencies and institutions worldwide, says that of the 15 indicators used to assess climate-related health risks, exposure, and impacts, 10 have already reached alarming levels.

Heat-related mortality among people over 65 rose by 167 per cent compared with the 1990s, 102 percentage points higher than a 65 per cent increase expected without temperature rise, says the report.

In 2023, children and adults over 65 experienced 13.8 days of heatwaves. This set a new per-person record, with heat exposure increasingly affecting physical activities and sleep quality, with consequent effects on physical and mental health. Heat exposure put people engaging in outdoor physical activity at risk for moderate or higher heat stress for 27.7 per cent more hours than the 1990s average, while lost sleep hours due to heat reached a record 6 per cent increase compared with the 1986-2005 average. There was also a loss of 512 billion potential work hours, a 49 per cent increase over the 1990-99 average.

People around the world are increasingly vulnerable to extreme climate events. According to the report, from 1961-90 to 2014-23, 61 per cent of global land area saw an increase in days of extreme rainfall, leading to heightened risks of flooding, infectious disease spread, and water contamination.

One notable impact is on the potential risk for dengue: Over the period between 1951-60 and 2014-23, climatic suitability for transmission by Aedes aegypti increased by 10.7 per cent. Over five million dengue cases were reported globally in 2023.

Meanwhile, 48 per cent of the global land area experienced at least one month of extreme drought in 2023, the second-largest expanse over which the phenomenon was recorded since 1951. Increased droughts and heatwaves from 1981 to 2010 contributed to 151 million people suffering moderate or severe food insecurity in 124 countries in 2022, the highest level on record, says the report.

Global CO₂ emissions from energy generation, the report says, hit a record high in 2023. Oil and gas companies are reinforcing global dependency on fossil fuels, with most planning to expand their operations, it notes. As of March 2024, the world’s 114 largest oil and gas companies were on track to exceed emissions aligned with the target of 1.5 °C by 189 per cent by 2040, compared with 173 per cent predicted in the previous year. This trajectory is clearly off course from meeting the Paris Agreement target of limiting global temperature increase to 1.5 °C, further threatening people’s health and survival.

“The latest Lancet Countdown report, to which WHO has been a strategic partner, makes it clear: Climate change is not a distant threat, but an immediate risk to health,” Director-General Tedros Adhanom Ghebreyesus of the WHO said.