Penning micro-trap for quantum computing

Trapped ions in radio-frequency traps are among the leading approaches for realizing quantum computers, because of high-fidelity quantum gates and long coherence times1-3. However, the use of radio-frequencies presents several challenges to scaling, including requiring compatibility of chips with high voltages4, managing power dissipation5 and restricting transport and placement of ions6. Here we realize a micro-fabricated Penning ion trap that removes these restrictions by replacing the radio-frequency field with a 3 T magnetic field. We demonstrate full quantum control of an ion in this setting, as well as the ability to transport the ion arbitrarily in the trapping plane above the chip. This unique feature of the Penning micro-trap approach opens up a modification of the quantum charge-coupled device architecture with improved connectivity and flexibility, facilitating the realization of large-scale trapped-ion quantum computing, quantum simulation and quantum sensing.

Bias in Error-Corrected Quantum Sensing

The sensitivity afforded by quantum sensors is limited by decoherence. Quantum error correction (QEC) can enhance sensitivity by suppressing decoherence, but it has a side effect: it biases a sensor's output in realistic settings. If unaccounted for, this bias can systematically reduce a sensor's performance in experiment, and also give misleading values for the minimum detectable signal in theory. We analyze this effect in the experimentally motivated setting of continuous-time QEC, showing both how one can remedy it, and how incorrect results can arise when one does not.

Pre-exposure prophylaxis for conception (PrEP-C) as a risk reduction strategy in HIV-positive men and HIV-negative women in the UK

Couples wishing to have biological children when one partner is HIV positive and the other is HIV negative present clinicians with complex clinical, social and ethical considerations. We established two multidisciplinary pre-conception services for HIV-positive individuals and their partners. We report the first UK use of pre-exposure prophylaxis for conception (PrEP-C) as part of an overall risk reduction strategy. Couples were counselled and written informed consent for PrEP-C was obtained. Patient demographics, HIV and medical histories were recorded. Males underwent baseline semen analysis and seminal HIV viral load testing. Females had full fertility screens. Both partners were screened for sexually transmitted infections. All couples used timed ovulatory intercourse (TOI). Tenofovir±emtricitabine was taken by the female at protocol designated times before±after TOI. Thirty-two male positive/female negative couples used the services. Thirteen couples have used PrEP-C (median age of male 41 years (range 32-56), female 31 (28-43); median CD4 533 (236-1194); all male plasma and seminal HIV viral loads were undetectable). Eleven pregnancies in 10 couples have resulted in 7 live births, 1 ongoing pregnancy and 4 miscarriages (5/40, 6/40, 10/40 and 1 twin 17/40) after a median of 2.5 attempts (range 1-5). PrEP-C was well tolerated with no discontinuations and no HIV transmissions. These data suggest that PrEP-C is a safe and effective option for serodiscordant couples wishing to conceive; a standardised protocol has been developed; data collection via a central database is under way.

Opportunistic testing for chlamydial infection in people attending a sexual medicine clinic for HIV tests

Patients presenting for an HIV test alone represent an opportunity for screening for Chlamydia trachomatis. This audit was designed to assess the uptake of chlamydial screening by urinary ligase chain reaction (LCR) in adults attending a genitourinary clinic. All patients requesting an HIV test were offered full genital screening in the first audit period, if they declined they were offered chlamydial LCR. During the second period patients who refused full screening were asked to provide a urine sample for LCR testing unless they declined. Nine hundred and forty-two patients presented for HIV tests alone during the first audit period. Two hundred (22%) agreed to provide a urine sample for LCR testing, 7 (3.5%) were positive for chlamydia. During the second audit period 794 patients presented for HIV tests alone, 426 (55.1%) provided urine for LCR testing, 15 (3.4%) were positive. The uptake of urinary LCR, a non-invasive test for a potentially serious infection remained disappointingly low despite changes to the audit protocol. Reasons for this are discussed.